Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session Q1: Poster Session III (4:00pm-6:00pm)Poster
|
Hide Abstracts |
Room: Exhibit Hall B |
|
Q1.00001: ATOMIC MAGNETOMETERS AND SENSORS |
|
Q1.00002: Atomic vapor spectroscopy in integrated photonic structures Tilman Pfau, Ralf Ritter, Nico Gruhler, Wolfram Pernice, Harald Kuebler, Robert Loew We investigate an integrated optical chip immersed in atomic vapor providing several waveguide geometries for spectroscopy applications [1]. This includes integrated ring resonators [2], Mach Zehnder interferometers, slot waveguides and counterpropagating coupling schemes. The narrow-band transmission through a silicon nitride waveguide and interferometer is altered when the guided light is coupled to a vapor of rubidium atoms via the evanescent tail of the waveguide mode. We use grating couplers to couple between the waveguide mode and the radiating wave, which allow for addressing arbitrary coupling positions on the chip surface. The evanescent atom-light interaction can be numerically simulated and shows excellent agreement with our experimental data. This work demonstrates a next step towards miniaturization and integration of alkali atom spectroscopy and provides a platform for further fundamental studies of strong atom light coupling. Cooperativities on the order of 1 are within reach. In the future integrated optical and electronic circuits in atomic vapor cells will enable applications in quantum sensing and quantum networks. [1] R. Ritter, et al., Appl. Phys. Lett. 107, 041101 (2015) [2] R. Ritter, et al., New Journal of Physics 18, 103031 (2016) [Preview Abstract] |
|
Q1.00003: DC Magnetometry at the T2 limit Ashok Ajoy, YiXiang Liu, Paola Cappellaro Sensing static or slowly varying magnetic fields with high sensitivity and spatial resolution is critical to many applications in fundamental physics, bioimaging and materials science. Several versatile magnetometry platforms have emerged over the past decade, such as electronic spins associated with Nitrogen Vacancy (NV) centers in diamond. However, their high sensitivity to external fields also makes them poor sensors of DC fields. Indeed, the usual method of Ramsey magnetometry leaves them prone to environmental noise, limiting the allowable interrogation time to the short dephasing time T2∗. Here we introduce a hybrid magnetometry platform, consisting of a sensor and an ancillary qubit, that allows sensing static magnetic fields with interrogation times up to the much longer T2 coherence time, allowing significant potential gains in field sensitivity. We demonstrate the method for an electronic NV sensor and a nuclear ancillary qubit. It relies on frequency up-conversion of transverse DC fields through the ancillary qubit, allowing quantum lock-in detection with low-frequency noise rejection, and ushers in a compelling technique for sensitive DC magnetometry at the nanoscale. [Preview Abstract] |
|
Q1.00004: Sensitivity Limits of Rydberg Atom-Based Radio Frequency Electric Field Sensing Akbar J. Jahangiri, Santosh Kumar, Harald Kuebler, Haoquan Fan, James P. Shaffer We present progress on Rydberg atom-based RF electric field sensing using Rydberg state electromagnetically induced transparency (EIT) in room temperature atomic vapor cells. In recent experiments on homodyne detection with a Mach-Zehnder interferometer and frequency modulation spectroscopy with active control of residual amplitude modulation we determined that photon shot noise on the probe laser detector limits the sensitivity. Another factor that limits the accuracy is residual Doppler broadening due to the wave-vector mismatch between the coupling and the probe lasers. The sensor as limited by project noise can be orders of magnitude better. A multi-photon scheme is presented that can eliminate the residual Doppler effect by matching the wave-vectors of three lasers and reduce the photon shot noise limit by correctly choosing the Rabi frequencies of the first two steps of the EIT scheme. Using density matrix calculations, we predict that the three-photon approach can improve the detection sensitivity to below 200 nV cm$^{\mathrm{-1\thinspace }}$Hz$^{\mathrm{-1/2\thinspace }}$and expand the Autler-Townes regime which improves the accuracy. [Preview Abstract] |
|
Q1.00005: Theoretical analysis of the oscillating frequency in spin-exchange optically pumped spin oscillators. Zhiguo Wang The atomic spin precesses continually when a positive feedback magnetic field is applied. The characteristics of this behaviour depend not only on the parameters of the spin ensemble but also on the feedback loop. We theoretically analyzed direct feedback and phase-lock feedback modes. We also compared the oscillating frequency of the spin oscillators driven by rotating and linear magnetic fields. In the direct feedback mode, the spin oscillator has a characteristic time of approximately twice the longitudinal relaxation time T$_{\mathrm{1}}$, whereas in the phase lock feedback mode, the characteristic time is approximately the transverse relaxation time T$_{\mathrm{2}}$ when T$_{\mathrm{2}}$\textless \textless T$_{\mathrm{1}}$. When the spin ensemble is driven by the rotating field, its oscillating frequency is $\omega =\omega_{\mathrm{0}}+$tan$\varphi $/T$_{\mathrm{2}}$, regardless of the feedback type. Here, $\omega _{\mathrm{0}}$ is the free Larmour frequency, and $\varphi $ is the phase shift of the feedback loop. When the spin ensemble is driven by the linear field, its oscillating frequency is much more complicated. These findings will be useful to improve the accuracy of fundamental physical theory tests, such as the Lorentz-violation and EDM test, using spin oscillators. [Preview Abstract] |
|
Q1.00006: Distribution of Rb atoms on the antirelaxation RbH coating. Yi Zhang, Zhiguo Wang, Tao Xia We observe the extension of relaxation time of $^{\mathrm{131}}$Xe with RbH coating, and compare the different depositions of Rb atoms on the inner surface of the vapor cell with and without RbH coating respectively to research the mechanism of coating prolongation. From the 5*5 um$^{\mathrm{2}}$ images of microscopy, we find that on the bare glass surface the Rb atoms form large random separated islands, and to the contrary they deposite as many regular longitudinal stripe of small islands on the RbH coating. We attribute these different distributions to the different molecular interactions between RbH coating and bare glass to Rb atom and build a simple rational physical model to explain this phenomenon. On the one hand, the small islands, or in other words, the relative uniform distribution on RbH coating may result from the relative stronger interaction of Rb to RbH than to the bare glass. On the other hand, the regular longitudinal stripe may stem from the grain boundaries which is related to the macroscopic shape of the vapor cell. And this longitudinal distribution can generate cylindrically electric gradient as used in some theoretically references before. [Preview Abstract] |
|
Q1.00007: A study of temperature control related factors in Vapor cell heating mechanism design for atomic sensor. Tao Xia, Zhiguo Wang, Yi Zhang Atomic sensor has become a very promising field of study in developing low cost, high-precision quantum measurement in a compact volume. A vapor cell which contains the working substance is usually a key element fo an atomic sensor. t is always necessary to maintain the working substance, such as alkali metal, in gas state with high density. The precision o th sensor is usually closely related to temperature stability and homogeneity of the working substance in the cell. his work studied different heat preservation, heater band or heating power arrangements, and heating rate settings in the cell heating mechanism design. Our study firstly shows that the better heat preservation we have, the better temperature stability we will obtain. It also shows that an appropriate control of power distribution in different heater band is important in ensuring a cold point in the cell, so that the solid state alkali metal will condense near a fixed cold point. And in order to ensure the fixed cold point always has a lower temperature when powering off the system, we should carefully control the heating power decrease for different heater band around the cell. At last, based on our study, we designed an optimized heating mechanism for atomic sensor implementation in the future. [Preview Abstract] |
|
Q1.00008: Study of magnetic resonance with parametric modulation in a potassium vapor cell Rui Zhang, Zhiguo Wang, Xiang Peng, Wenhao Li, Songjian Li, Hong Guo A typical magnetic-resonance scheme employs a static bias magnetic field and an orthogonal driving magnetic field oscillating at the Larmor frequency, at which the atomic polarization precesses around the static magnetic field. We demonstrate in a potassium vapor cell the variations of the resonance condition and the spin precession dynamics resulting from the parametric modulation of the bias field, which are in well agreement with theoretical predictions from the Bloch equation. We show that, the driving magnetic field with the frequency detuned by different harmonics of the parametric modulation frequency can lead to resonance as well. Also, a series of frequency sidebands centered at the driving frequency and spaced by the parametric modulation frequency can be observed in the precession of the atomic polarization. These effects could be used in different atomic magnetometry applications. [Preview Abstract] |
|
Q1.00009: An NV-Diamond Magnetic Imager for Neuroscience Matthew Turner, Jennifer Schloss, Erik Bauch, Connor Hart, Ronald Walsworth We present recent progress towards imaging time-varying magnetic fields from neurons using nitrogen-vacancy centers in diamond. The diamond neuron imager is noninvasive, label-free, and achieves single-cell resolution and state-of-the-art broadband sensitivity. By imaging magnetic fields from injected currents in mammalian neurons, we will map functional neuronal network connections and illuminate biophysical properties of neurons invisible to traditional electrophysiology. Furthermore, through enhancing magnetometer sensitivity, we aim to demonstrate real-time imaging of action potentials from networks of mammalian neurons. [Preview Abstract] |
|
Q1.00010: Detecting Magnetic Monopoles in Spin Ice with NV-magnetometry Felix Flicker, Franziska Kirschner, Norman Yao, Stephen Blundell Magnetic monopoles, isolated north and south poles, appear not to exist as fundamental particles in our universe. Nevertheless, it has been proposed that they may emerge as quasiparticles in certain materials: the geometrically-frustrated `spin ice' pyrochlores dysprosium and holmium titanate. Despite a great deal of experimental and theoretical work, the smoking gun signature of magnetic monopoles in spin ice remains to be discovered. A promising candidate for the detection of individual magnetic monopoles comes in the form of Nitrogen-Vacancy (NV) defects in diamond, which act as very sensitive probes of vector magnetic fields on the nanometre scale. We present the result of Monte Carlo modeling for the precise signals one would expect to see with nanometre-scale probes such as NV-magnetometers or muon spin rotation. [Preview Abstract] |
|
Q1.00011: SQCRAMscope imaging of transport in an iron-pnictide superconductor Fan Yang, Alicia Kollar, Stephen Taylor, Johanna Palmstrom, Jiun-Haw Chu, Ian Fisher, Benjamin Lev Microscopic imaging of local magnetic fields provides a window into the organizing principles of complex and technologically relevant condensed matter materials. However, a wide variety of intriguing strongly correlated and topologically nontrivial materials exhibit poorly understood phenomena outside the detection capability of state-of-the-art high-sensitivity, high-resolution scanning probe magnetometers. We have recently introduced a quantum-noise-limited scanning probe magnetometer that can operate from room-to-cryogenic temperatures with unprecedented DC-field sensitivity and micron-scale resolution. The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) employs a magnetically levitated atomic Bose-Einstein condensate (BEC), thereby providing immunity to conductive and blackbody radiative heating. We will report on the first use of the SQCRAMscope for imaging a strongly correlated material. Specifically, we will present measurements of electron transport in iron-pnictide superconductors across the electron nematic phase transition at T = 135 K. [Preview Abstract] |
|
Q1.00012: Optical Magnetometry using Multipass Cells with overlapping beams Nathaniel David McDonough, Vito Giovanni Lucivero, Nezih Dural, Michael Romalis In recent years, multipass cells with cylindrical mirrors have proven to be a successful way of making highly sensitive atomic magnetometers. In such cells a small laser beam makes 40 to 100 passes within the cell without significant overlap with itself. Here we describe a new multi-pass geometry which uses spherical mirrors to reflect the probe beam multiple times over the same cell region. Such geometry reduces the effects of atomic diffusion while preserving the advantages of multi-pass cells over standing-wave cavities, namely a deterministic number of passes and absence of interference. We have fabricated several cells with this geometry and obtained good agreement between the measured and calculated levels of quantum spin noise. We will report on our effort to characterize the diffusion spin-correlation function in these cells and operation of the cell as a magnetometer. [Preview Abstract] |
|
Q1.00013: Electrometry and Quantum Memory With Rydberg Atoms David Meyer, Kevin Cox, Fredrik Fatemi, Paul Kunz Rydberg states of atoms with large principle quantum number $n$ have extreme sensitivity to electric fields, with dipole moments that scale as $n^2$. These states are promising for applications in precision measurement of microwave electric fields and open new possibilities in quantum information science. First we present an experiment that uses thermal Rydberg atoms to measure amplitude-modulated (AM) RF fields. Amplitude modulation can improve state-of-the-art sensitivities already achieved using Rydberg atoms, and through AM we demonstrate a phase-shift-keying communication protocol. In addition, we present progress on a new experiment to trap laser-cooled Rydberg atoms in an optical cavity where the Rydberg blockade may allow a deterministic and high fidelity quantum memory for a high entanglement rate quantum repeater. [Preview Abstract] |
|
Q1.00014: Progress towards a primary, ultracold-atom-based pressure standard in the XHV regime Daniel S. Barker, Julia K. Scherschligt, Nikolai N. Klimov, James A. Fedchak, Stephen Eckel Preparation and evaluation of ultra-high-vacuum (UHV) and extreme-high-vacuum (XHV) environments is critical for high-quality semiconductor fabrication and emerging quantum technologies. Vacuum sensors for these pressure ranges, such as ion-gauges, are not primary (i.e., they require calibration themselves) and have large, poorly-understood uncertainties. We present our progress towards a primary standard for vacuum measurement in the XHV using a gas of ultra-cold atoms confined in a magnetic trap. Our apparatus will allow high-accuracy measurements of atom-molecule collision cross-sections that are necessary to extract the vacuum pressure from the observed background-gas-limited lifetime of the trapped atoms. We are also developing a chip-scale atom trap that integrates all the optics and electromagnets required to create magnetically-trapped, ultra-cold gases. This nano-fabricated atom-trapping chip will form the basis for a deployable, primary vacuum sensor with embedded traceability that can replace an ion gauge. [Preview Abstract] |
|
Q1.00015: Magnetic imaging of magnetotactic bacteria using NV centers in diamond Chenchen Luo, Pauli Kehayias, Matthieu Amor, David Glenn, Arash Komeili, Ronald Walsworth Nitrogen-vacancy (NV) centers in diamond can be used for room-temperature magnetometry with high spacial resolution (< 1 micron). We use NV magnetic microscopy to image the magnetic fields produced by magnetotactic bacteria (MTB), which produce intracellular chains of 50 nm ferromagnetic particles to orient themselves in the Earth's magnetic field. We will present recent advances on using this magnetic imaging tool to further understand how these particles are formed, how different genes and proteins influence particle formation, and other biomagnetism questions. [Preview Abstract] |
|
Q1.00016: Paleomagnetism studies with NV widefield magnetic microscopy David Glenn, Roger Fu, Pauli Kehayias, Eduardo Lima, Chenchen Luo, Benjamin Weiss, Ronald Walsworth We will discuss using nitrogen-vacancy (NV) defect centers in diamond to measure the magnetic field of rock samples for paleomagnetism analysis. NV magnetic microscopy achieves micron-scale spatial resolution that is otherwise inaccessible for rock paleomagnetism studies. This enables us to spatially distinguish between different ferromagnetic minerals and isolate high-coercivity magnetic inclusions from possible contamination. In addition to presenting continuing sensitivity and instrumentation improvements, we will describe ongoing paleomagnetism measurements, including constraining the magnetic field strength of the early Earth and assessing whether meteorite parent bodies had magnetic dynamo activity. [Preview Abstract] |
|
Q1.00017: Towards NV-based magnetic sensing in the time domain Elana Urbach, Tamara Sumarac, Igor Lovchinsky, Renate Landig, Javier Sanchez-Yamagishi, Trond Andersen, Hongkun Park, Mikhail Lukin The study of protein folding dynamics is an outstanding problem in the biological sciences. We show that nitrogen-vacancy (NV) centers in diamond can be used to dynamically sense the conformational states of individual proteins under ambient conditions. We present preliminary data on time-domain detection of electronic spin labels which were chemically attached to the proteins, as well as label-free detection of native hydrogen nuclear spins within the protein. In addition, we discuss work~towards polarizing boron-11 spins in atomically-thin hexagonal boron nitride using Hartmann-Hahn double resonance, with the ultimate goal of studying many-body spin dynamics and performing quantum simulation. [Preview Abstract] |
|
Q1.00018: Imaging strain gradients inside a diamond anvil cell using Nitrogen-Vacancy Centers in Diamond Satcher Hsieh, Thomas Mittiga, Chong Zu, Thomas Smart, Bryce Kobrin, Viktor Struzhkin, Raymond Jeanloz, Norman Yao Since their introduction, diamond anvil cells have become the most versatile approach to generating sustained high pressures inside the laboratory. By compressing a thin sample between two opposing diamonds, pressures over hundreds of gigapascal can be achieved. Despite their ubiquity, little is known about the internal mechanical response of the diamond anvil at such high pressures. By imaging ensembles of nitrogen-vacancy centers, we perform experimental measurements of strain gradients over a millimeter-size volume under gigapascal pressures. Our results inform the optimization of high pressure cell designs and demonstrate the integration of nitrogen-vacancy centers as atomic scale sensors in high pressure research. [Preview Abstract] |
|
Q1.00019: Study of Harmful Algae Blooms Using UAS Imagery Ileana Dumitriu, Peter Spacher, John Halfman Harmful Algal Blooms (HABs) occurrence has increased in recent decades. The transient nature of HABs in both space and time result in monitoring challenges, which add to the difficulty in understanding the criteria that trigger HABs. Traditional monitoring programs are expensive and time consuming. The use of UAS (Unmanned Aerial Systems) assures high-resolution space and time monitoring for HABs, and is economical for small bodies of water. By using UAS (Matrice100 and Phantom3) we obtained aerial photographs of eight Finger Lakes which span the oligotrophic to eutrophic spectrum of algal productivity. Water samples were collected and analyzed simultaneously. The Green/Blue (G/B) ratio extracted from the aerial photos was proportional to chlorophyll-a abundance. The algal pigments are also characterized by unique light absorbance and reflectance features, and spectral images obtained from two up-down visible spectrometers revealed a prominent feature \textasciitilde 790 nm which correlates to the concentration of algae in the water. [Preview Abstract] |
|
Q1.00020: PRECISION MEASUREMENT |
|
Q1.00021: Testing the Rotation Stage in the ARIADNE Axion Experiment Jordan Dargert, Chloe Lohmeyer, Mindy Harkness, Mark Cunningham, Harry Fosbinder-Elkins, Andrew Geraci The Axion Resonant InterAction Detection Experiment (ARIADNE) will search for the Peccei-Quinn (PQ) axion, a hypothetical particle that is a dark matter candidate. Using a new technique based on Nuclear Magnetic Resonance, this new method can probe well into the allowed PQ axion mass range [1]. Additionally, it does not rely on cosmological assumptions, meaning that the PQ Axion would be sourced locally. Our project relies on the stability of a rotating segmented source mass and superconducting magnetic shielding. Superconducting shielding is essential for limiting magnetic noise, thus allowing a feasible level of sensitivity required for PQ Axion detection. Progress on testing the stability of the rotary mechanism will be reported, and the design for the superconducting shielding in the experiment will be discussed, along with plans for moving the experiment forward. [1] A. Arvanitaki and A. Geraci, Phys. Rev. Lett. 113, 161801 (2014) [Preview Abstract] |
|
Q1.00022: Measurement of parity non-conservation in cesium using two-pathway coherent control Yao De George Toh, Jungu Choi, Daniel Elliott Atomic parity violation measurements provide a way to probe physics beyond the Standard Model. They can provide constraints on conjectures of a massive \(Z'\) boson or a light boson, or searches of dark energy. Using the two-pathway coherent control techniques developed by our group, we plan a new measurement of \(E_{PNC}\) on the cesium 6S \(\rightarrow\) 7S transition. We coherently interfere a 2-photon transition with the Stark and PNC transition to amplify and extract the PNC amplitude. This should result in much smaller systematic effects as compared to those of previous measurements of \(E_{PNC}\). Previously, we have measured the magnetic dipole transition moment on the same 6S \(\rightarrow\) 7S transition to about 0.4\% uncertainty. We discuss improvements made to the system to date and our plans for further upgrades towards an \(E_{PNC}\) measurement. Key systematics and how we plan to overcome them will also be detailed. [Preview Abstract] |
|
Q1.00023: Using Global Network Precision Measurements to Search for Exotic Physics Alex Rollings, Benjamin Roberts, Geoffrey Blewitt, Conner Dailey, Maxim Pospelov, Jeff Sherman, Wyatt Williams, Andrei Derevianko The Global Positioning System (GPS) comprises of a constellation of approximately 30 Medium-Earth Orbit satellites equipped with either Cs or Rb atomic clocks, as well as a number of Earth-based receiver stations, many of which employ highly-stable H-maser clocks. More than a decade's worth of high accuracy GPS timing data is currently available. Such a constellation provides a unique opportunity; by analyzing the satellite and terrestrial atomic clock data, it is possible to search for transient signatures of exotic physics, such as dark matter and dark energy. In effect, we utilize the GPS constellation as a 50,000 km aperture dark matter detector. In this poster, we outline some of the details and challenges involved in employing such a network for fundamental physics research, in particular the Bayesian analysis methods that we use for the search. These methods do not only apply to the GPS atomic clocks. Similar approaches can be used for networks of ground-based atomic clocks, magnetometers, gravimeters, and any other precision measurement tools. A. Derevianko and M. Pospelov, Nat. Phys. 10, 933 (2014) [Preview Abstract] |
|
Q1.00024: Progress towards measuring the Rydberg constant with circular Rydberg atoms Andira Ramos, Kaitlin Moore, Georg Raithel An experiment to measure the Rydberg constant independently of nuclear-charge effects, such as the currently ambiguous proton-size puzzle, is underway. Cooled and trapped circular rubidium Rydberg atoms will be utilized for the measurement. These states, obtained by using the adiabatic rapid passage method (ARP), have the advantages of having lifetimes in the order of milliseconds, small QED corrections, and no ionic-core and nuclear-charge overlaps. The transition of interest will be driven via amplitude modulation of a three-dimensional standing-wave light field the atoms are immersed in, which results in a Doppler-free spectroscopic signal. In this poster, we discuss the design and construction of the circularization, field control and lattice schemes for this experiment. [Preview Abstract] |
|
Q1.00025: Quantum measurement and control of rapidly rotating single qubits in diamond Alexander Wood, Emmanuel Lilette, Yaakov Fein, Liam McGuinness, David Simpson, Alastair Stacey, Jean-Phillipe Tetienne, Lloyd Hollenberg, Robert Scholten, Andy Martin Internal state rotations are a ubiquitous feature of quantum mechanics, but the effects of physical rotation on a qubit are less widely understood. Rotation induces interesting physics, such as geometric phase accumulation in a rotating qubit, as well as concomitant challenges. The nitrogen-vacancy (NV) center in diamond is a highly versatile quantum sensor, capable of probing magnetic fields, electric fields, crystal strain and temperature in real-world sensing environments. The NV is a propitious candidate for observing the effects of physical rotation on a single qubit, for example as a nanoscale gyroscope. In this work we demonstrate optical addressing and quantum state manipulation of single NV centers within a diamond mechanically rotated with a period comparable to the spin dephasing time $T_2$. Our results demonstrate measurements of single qubits rotating with high angular velocities, and establish the experimental techniques required to control and extract quantum information from rapidly moving NV centers. [Preview Abstract] |
|
Q1.00026: Atomic Spectroscopy of the Solar Atmosphere to Enable Earth-like Exoplanet Detection Timothy Milbourne, Nicholas Langellier, Aakash Ravi, Christian Dolliff, David Phillips, Ronald Walsworth The radial velocity (RV) method has proved to be one of the most prolific means of exoplanet detection. This technique uses measurements of periodic Doppler shifts of the stellar spectrum to deduce the mass and semi-major axis of orbiting exoplanets. The detection an Earth-like exoplanet orbiting a Sun-like star requires RV sensitivity below 10 cm/s (corresponding to kHz shifts of GHz-wide spectral lines). The installation of a laser-frequency ``astro-comb'' at the High Accuracy Radial velocity Planet Search for the Northern Hemisphere (HARPS-N) spectrograph on La Palma has enabled such observations. Exoplanet measurements is now limited by the noise of the stars themselves: sunspots, convection, and other types of stellar activity produce RV variations on the order of m/s, far above the detection threshold for Earth-like planets. Here, we use the Sun as a test case to better understand RV variations due to stellar activity. By comparing solar spectra taken by a purpose-built Solar Telescope on La Palma with images taken by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), we hope to identify feature in the solar spectrum which are correlated with solar activity. Such correlates will allow us to build more sophisticated models of stellar activity, and will enable more precise measurements of Earth-like exoplanets. [Preview Abstract] |
|
Q1.00027: High-precision atomic structure measurements in lead Eli Hoenig, P.M. Rupasinghe, P.K. Majumder Two high-precision measurements of atomic parity nonconservation in lead were completed more than two decades ago. The ability of these results to test the Electroweak Standard Model was limited, however, by the poor accuracy of lead atomic structure calculations. Very recently, significantly improved wavefunction calculations in lead suggest that a new, precise electroweak test in this system may be possible\footnote{Porsev \textit{et al.}, Phys. Rev. \textbf{A} 93, 012501 (2016)}. We have undertaken new measurements of atomic structure properties of lead to test the new calculations and guide their further refinement. Using both direct absorption and Faraday optical rotation techniques, we are measuring isotope shifts and $^{207}$Pb hyperfine structure splittings in ground-state transitions. In particular we are measuring the electric quadrupole $6P_{0} \rightarrow 6P_{2}$ transition amplitude relative to the more-easily-calculable $6P_{0} \rightarrow 6P_{1}$ magnetic dipole amplitude. The high sensitivity of our optical rotation technique allows the E2 and M1 absorptivities to be measured simultaneously in the same cell, even though the E2 transition strength is approximately two orders of magnitude smaller. Current experimental results will be presented. [Preview Abstract] |
|
Q1.00028: All-Optical Nanoscale Thermometry using Silicon-Vacancy Centers in Diamond Christian Nguyen, Ruffin Evans, Alp Sipahigil, Mihir Bhaskar, Denis Sukachev, Mikhail Lukin Accurate thermometry at the nanoscale is a difficult challenge, but building such a thermometer would be a powerful tool for discovering and understanding new processes in biology, chemistry and physics. Applications include cell-selective treatment of disease, engineering of more efficient integrated circuits, or even the development of new chemical and biological reactions. In this work, we study how the bulk properties of the Silicon Vacancy center (SiV) in diamond depend on temperature, and use them to measure temperature with \begin{figure}[htbp] \centerline{\includegraphics[width=1.97in,height=0.91in]{270120171.eps}} \label{fig1} \end{figure} 100mK accuracy. Using SiVs in \begin{figure}[htbp] \centerline{\includegraphics[width=1.89in,height=0.91in]{270120172.eps}} \label{fig2} \end{figure} 200nm nanodiamonds, we measure the temperature with \begin{figure}[htbp] \centerline{\includegraphics[width=1.89in,height=0.91in]{270120173.eps}} \label{fig3} \end{figure} 100nm spatial resolution over a 10$\mu $m area. [Preview Abstract] |
|
Q1.00029: High-precision polarizability measurements in excited states of indium using two-step spectroscopy in an atomic beam Nathaniel Vilas, P.M. Rupasinghe, P.K. Majumder Recent measurements in our group of indium scalar polarizability within two low-lying transitions showed excellent agreement with {\textit ab initio} atomic theory at the 1-2\% level. We are now completing measurements of the polarizability within the $6s_{1/2} \rightarrow 7p_{1/2,3/2}$ excited-state transitions. In our experiment, two external cavity semiconductor diode lasers interact transversely with a collimated indium atomic beam. We tune a 410 nm laser to the $5p_{1/2} \rightarrow 6s_{1/2}$ transition, keeping the laser locked to the exact Stark-shifted resonance frequency. We overlap a second (685 or 690 nm) laser to reach the $7p$ excited states, using lock-in detection to observe its very small absorption in the atomic beam. Monitoring the two-step excitation signal in a field-free supplemental vapor cell provides frequency reference and calibration. Scalar polarizabilities for the $7p$ states are 1-2 orders of magnitude larger than in previously measured transitions, so that application of modest, precisely calibrated electric fields of a few kV/cm produce Stark shifts of order 100 MHz. Fields of order 15 kV/cm can also be applied in order to extract the tensor polarizability of the $7p_{3/2}$ state. Experimental details and latest results will be presented. [Preview Abstract] |
|
Q1.00030: Atomic Spectroscopy and Gaussian Processes to Enable Earth-like Exoplanet Detection Nicholas Langellier, Timothy Milbourne, Aakash Ravi, Christian Dolliff, David Phillips, Ronald Walsworth Precision radial velocity (PRV) exoplanet astronomy has reached a critical sensitivity barrier in the detection of Earth-like planets. We describe techniques to overcome this barrier. We have developed a small solar telescope located in the Canary Islands, which we use to observe the Sun as a point source of light, i.e., as if it was a distant star.~ We are employing methods from atomic spectroscopy and Gaussian processes to analyze the Sun-as-a-star data, and thereby to understand systematic effects on PRV signals arising from ``stellar jitter" (oscillations, sunspots, etc.). [Preview Abstract] |
|
Q1.00031: Proposal for Two-Photon Doppler-Free Extreme Ultraviolet Direct Frequency Comb Spectroscopy of the Helium Ground State Gil Porat, Christoph M. Heyl, Stephen B. Schoun, Jun Ye Tests of quantum electrodynamics (QED) are part of the search for physics beyond the standard model. QED calculations are most precise in simple systems, e.g., few-electron atoms. Hydrogen spectroscopy yielded the most stringent test so far, however QED effects are stronger in helium ground state transitions. Furthermore, experimental results disagree on the $^3He-^4He$ nuclear charge radius difference, measured using excited state transitions. This discrepancy might be related to the proton radius puzzle, and could potentially be resolved by measuring a helium ground state transition, where the effect of the nucleus is greatest. However, such transitions are in the extreme ultraviolet (XUV), where the only available stabilized laser is a frequency comb, which has so far lacked sufficient power for direct spectroscopy. We propose to perform direct two-photon frequency comb spectroscopy of the 20.6eV $1^1S-2^1S$ transition in helium, using a cell of cryogenic helium. This approach just became available, due to our success in scaling the power of our XUV frequency comb. The use of cold ($\sim$4K) helium gas significantly reduces transit-time broadening and also allows for high gas densities. We expect to achieve the first spectroscopic measurement in the XUV with sub-MHz precision. [Preview Abstract] |
|
Q1.00032: Development of a position sensitive detector for Rydberg atom experiments Melina Fuentes-Garcia, Adric Jones, Jeremy Moxom, Daniel Adams, Gabriel Cecchini, Harris Rutbeck-Goldman, Kevin Osorno, Rod Greaves, Harry Tom, Allen Mills Since their invention, resistive anodes have played an important role in the imaging systems of many experiments. They are commonly used in conjunction with micro-channel plate detectors, which can greatly enhance the positional sensitivity. It is well known that the use of a square anode results in significant distortion in the positional mapping, which can be resolved by careful shaping of the anode. Here we utilize a square anode and correct the position data in post-analysis. We describe the development of such a paired system for use in our positronium (Ps) beam line, designed specifically for the detection of Rydberg Ps atoms. The first experimental results obtained with the detector demonstrated the focusing of a beam of Rydberg Ps by means of an electrostatic mirror. By employing a larger scale version of this apparatus, it should be possible to measure the gravitational deflection of Rydberg Ps atoms in Earth's field to high precision. [Preview Abstract] |
|
Q1.00033: Fetal Magnetocardiography with an Atomic Magnetometer Array Michael Bulatowicz, Zack DeLand, Lena Zhivun, Alec Hryciuk, Ron Wakai, Thad Walker We present the results of fetal magnetocardiography utilizing an array of four atomic magnetometers with simultaneous two-vector-component detection of magnetic fields resulting from a fetal heartbeat. Each magnetometer in the array contains an individual cell with 87Rb and buffer gas, operated in a SERF regime using orthogonal pump and probe beams, combined with parametric modulation along the pump beam for simultaneous two-vector-component detection of magnetic fields with a noise floor around 5 fT/rtHz. This work is supported by the National Institutes of Health. [Preview Abstract] |
|
Q1.00034: Ionization potentials of superheavy elements No, Lr, and Rf and their ions Marianna Safronova, Vladimir Dzuba, Ulyana Safronova, Alexander Kramida We predict ionization potentials of superheavy elements No, Lr, and Rf and their ions using a relativistic hybrid method that combines configuration interaction (CI) with the linearized coupled-cluster approach. We expect these values to be accurate to about 350 cm$^{−1}$. Extensive study of the completeness of the four-electron CI calculations for Hf and Rf was carried out. As a test of theoretical accuracy, we also calculated ionization potential of Yb, Lu, Hf, and their ions, which are homologues of the superheavy elements of this study. The test demonstrated that the CI+all-order method is capable of predicting ionization potentials of ions with 1 to 4 valence electron to a very good precision, which may be used to provide improved recommended data. [Preview Abstract] |
|
Q1.00035: Precision Measurements with a Dual Species NMR Oscillator Susan Sorensen, Daniel Thrasher, Joshua Weber, Anna Korver, Thad Walker We present progress towards a dual species nuclear magnetic oscillator using synchronous spin exchange optical pumping. By applying the bias field as a sequence of alkali 2$\pi$n pulses, we generate alkali polarization transverse to the bias field. The alkali polarization is then modulated at the noble gas resonance so that through spin exchange collisions the noble gas becomes polarized. This novel method of NMR suppresses the alkali field frequency shift by at least a factor of 2500 as compared to longitudinal NMR. We will present a detailed noise analysis of the apparatus as well as plans for measuring earth’s rotation. [Preview Abstract] |
|
Q1.00036: Ultralight dark matter signatures in precision measurements Andrei Derevianko Virialized Ultra-Light Fields (VULFs) while being viable cold dark matter candidates can in a certain parameter space also solve the standard model hierarchy problem. Direct searches for VULFs due to their non-particle nature require low-energy precision measurement tools. While the previous proposals have focused on detecting coherent oscillations of the measured signals at the VULF Compton frequencies, here we exploit the fact that VULFs are essentially dark matter {\em waves} and as such they carry both temporal and spatial phase information. Thereby the discovery reach can be improved by using distributed networks of precision measurement tools. We find the expected dark-matter signal by deriving the spatio-temporal two-point VULF correlation function. Based on the developed understanding of coherence properties of dark-matter fields, we propose several experiments for dark matter wave detection. In the most basic version, the modifications to already running experiments are minor and only require GPS-assisted time-stamping of data. We also derive the expected dark matter line profile for individual detectors. [Preview Abstract] |
|
Q1.00037: Constraining dark energy scalar fields using atom interferometry Victoria Xu, Matt Jaffe, Philipp Haslinger, Paul Hamilton, Amol Upadhye, Benjamin Elder, Justin Khoury, Holger Mueller Atom interferometry has proven to be a technique capable of making precise gravitational measurements. Typically however, these measurements probe the gravitational forces of large source masses, such as the Earth. We perform atom interferometry in an optical cavity near a centimeter-sized, in-vacuum source mass. By observing the gravitational attraction between a 190 gram miniature source mass and atoms for the first time, our measurement is sensitive to a wide class of screened scalar fields which would manifest as a fifth-force with a matter coupling as weak as gravity, a natural lower bound for fundamental forces. In particular, we improve our previous limits on ``screened'' scalar field theories which can reproduce the observed cosmic acceleration by over two orders of magnitude. [Preview Abstract] |
|
Q1.00038: TOPOLOGICAL QUANTUM MATTER |
|
Q1.00039: Exactly solvable interacting number-conserving models with Majorana-like ground states Zhiyuan Wang, Youjiang Xu, Han Pu, Kaden Hazzard Majorana fermions have sparked interest in condensed matter and cold atoms as emergent quasiparticles with fundamentally new properties, in particular non-Abelian statistics. However, most theoretical calculations start with a Bogoliubov mean-field approximation from which it is shown that the resulting model supports Majorana states. It then remains an open question whether and when this mean-field approximation is valid. We make progress towards this question in two ways. First, we demonstrate a model in which mean-field theory incorrectly predicts a gapped phase with Majorana ground states, whereas an unbiased DMRG calculation predicts a gapless phase instead. Second, we construct new families of exactly solvable interacting models, including a one-dimensional double wire lattice model and a two dimensional p+ip superconducting model. Significantly, these models are number-conserving but nevertheless can be shown to host robust Majorana-like degenerate ground states in the presence of edges and vortices. These results give a deeper conceptual understanding of how Majorana fermions can be realized in practice. [Preview Abstract] |
|
Q1.00040: Topology transfer from interacting systems to free lattice fermions Rui Li, Dominik Linzner, Michael Fleischhauer We show that the topological properties of an interacting, one-dimensional lattice system can be transferred to non-interacting lattice fermions by proximity coupling. A cylic variation of parameters in the interacting system, corresponding to a topological Thouless pump, is shown to result in a quantized fractional charge transport of the free fermions. We argue that this transfer of topological properties can be used to detect topological invariants of interacting systems with the potential advantage of being insensitive to topological excitations, which limit interferometric schemes [1]. We discuss in particular the extended superlattice Bose-Hubbard model (SLBHM) in one spatial dimension at quarter filling which has a degenerate ground state and fractional topological phases. Proximity coupling to a one-dimensional lattice of non interacting fermions leads to the formation of an incompressible phase of the fermions at quarter filling. Performing a Thouless pump in the SLBH system would result in a quantized charge transport in the fermionc system. We analyze the robustness of the induced charge pump and argue that it allows to detect the fractional Chern number associated with the SLBHM even in the presence of defects. [1] F. Grusdt et. al. Nature Comm. 7, 11994 (2016) [Preview Abstract] |
|
Q1.00041: Disordered wires and quantum chaos in a momentum-space lattice Eric Meier, Fangzhao An, Jackson Angonga, Bryce Gadway We present two topics: topological wires subjected to disorder and quantum chaos in a spin-J model. These studies are experimentally realized through the use of a momentum-space lattice, in which the dynamics of $^{87}$Rb atoms are recorded. In topological wires, a transition to a trivial phase is seen when disorder is applied to either the tunneling strengths or site energies. This transition is detected using both charge-pumping and Hamiltonian-quenching techniques. In the spin-J study we observe the effects of both linear and non-linear spin operations by measuring the linear entropy of the system as well as the out-of-time order correlation function. We further probe the chaotic signatures of the paradigmatic kicked top model. [Preview Abstract] |
|
Q1.00042: Ultracold atom dynamics in tailored disorder and synthetic gauge fields Fangzhao An, Eric Meier, Bryce Gadway Ultracold atoms in optical lattices have shown to be a versatile and useful platform for investigating a wide range of transport phenomena. Here we extend the range of cold atom quantum simulation with key advances in the study of both disordered and topological systems. By controlling laser-driven dynamics of a $^{\mathrm{87}}$Rb condensate in a momentum-space lattice, we demonstrate and apply our ability to engineer arbitrary patterns of disorder and flux (and thus field strength). We compare the dynamical responses to static tunneling phase disorder, dynamically-varying phase disorder akin to coupling with a thermal bath, and quasiperiodic site energy disorder. We study synthetic gauge fields in both a two-leg square ladder geometry and a zig-zag ladder geometry. We present measurements of chiral edge states in a uniform flux ladder, and of quantum reflection in the presence of an effective magnetic defect. We show similar flux-dependent dynamics in the zig-zag ladder, and further observe a flux-dependent metal-insulator transition in the presence of quasiperiodic disorder. [Preview Abstract] |
|
Q1.00043: Topological states of photons in coupled microwave cavities John Owens, Aman LaChapelle, Ruichao Ma, Brendan Saxberg, Jonathan Simon, David Schuster We present recent results in using coupled cavity arrays to explore quantum many-body phenomena. We create tight binding lattices with arrays of evanescently coupled three-dimensional coaxial microwave cavities. Topologically non-trivial band structures are engineered by utilizing the chiral coupling of the cavity modes to ferrite spheres in a magnetic field. Using screws made of different dielectric material, we can control every lattice site frequency, loss, and coupling strength to its neighbors. We then can probe each lattice site and measure the band structure, the edge dispersion, and time-resolved dynamics of pulses we inject at a particular site. These lattices can be cooled to superconducting temperatures to realize low disorder, long-coherence, topological tight binding models that are compatible with effective onsite photon-photon interactions by coupling lattice sites to superconducting qubits. This will allow us to explore the interplay between topology and coherent interaction in these artificial strongly-correlated photonic quantum materials. [Preview Abstract] |
|
Q1.00044: Symmetry-based dissipative preparation of matrix product states Leo Zhou, Soonwon Choi, Mikhail Lukin Matrix product states (MPS) are a powerful class of many-body entangled states capable of describing a variety of quantum systems in 1D, including all symmetry-protected topological (SPT) phases. The symmetry of an MPS can be exploited for a simple scheme that prepares the state dissipatively. As an example, we provide an explicit scheme to prepare the Affleck-Kennedy-Lieb-Tasaki (AKLT) states, which exhibit spin-1 SPT order characterized by string order parameters and spin-1/2 degrees of freedom on the boundary. In our scheme, we harness the symmetry of the AKLT parent Hamiltonian to design a simple driven-dissipative dynamics requiring only global control, under which an arbitrary initial state deterministically evolves into one of the ground states. The use of symmetry allows for robust experimental implementation where no fine-tuning of control parameters is required while still leading to an exact steady state. We demonstrate our scheme via numerical simulations, and propose an efficient method using parallelization to prepare the quantum state even in large system sizes. A concrete protocol for implementation in an array of trapped neutral atoms is also presented. [Preview Abstract] |
|
Q1.00045: Holographic driving and probing of a twisted optical resonator for exploration of topological physics Nathan Schine, Michelle Chalupnik, Jonathan Simon Nontrivial topology is at the heart of a host of intriguing phenomena in condensed matter physics. Synthetic materials consisting of a quantum gas of photons or ultracold atoms have established themselves as ideal systems to explore these phenomena. As experiments push into the strongly-interacting, strongly-correlated regime, characterizing topological many-body states through measurements of topological quantum numbers becomes critical. We present a real-space Chern number measurement in a photonic integer quantum Hall system, produced in a degenerate manifold of a multimode non-planar ring resonator. We will present how we control the spatial excitation of the resonator and perform holographic reconstruction of the resulting modes. From this, we measure arbitrary `band projectors' from which the Chern number is calculated. This system and measurement technique is compatible with strong interactions via cavity Rydberg electromagnetically induced transparency, enabling the preparation and characterization of novel manybody quantum states. [Preview Abstract] |
|
Q1.00046: DYNAMICS OF COLD ATOMS IN OPTICAL LATTICES |
|
Q1.00047: Quench-induced resonant tunneling mechanisms of bosons in an optical lattice with harmonic confinement Simeon Mistakidis, Georgios Koutentakis, Peter Schmelcher The non-equilibrium dynamics of small boson ensembles in one-dimensional optical lattices is explored upon a sudden quench of an additional harmonic trap from strong to weak confinement. We find that the competition between the initial localization and the repulsive interaction leads to a resonant response of the system for intermediate quench amplitudes, corresponding to avoided crossings in the many-body eigenspectrum with varying final trap frequency. In particular, we show that these avoided crossings can be utilized to prepare the system in a desired state. The dynamical response is shown to depend on both the interaction strength as well as the number of atoms manifesting the many-body nature of the tunneling dynamics. [Preview Abstract] |
|
Q1.00048: Multipulse interaction quenched ultracold few-bosonic ensembles in finite optical lattices Simeon Mistakidis, Jannis Neuhaus-Steinmetz, Peter Schmelcher The correlated non-equilibrium dynamics following a multipulse interaction quench protocol in few-bosonic ensembles confined in finite optical lattices is investigated. The multipulse interaction quench gives rise to the cradle [1,2] and a global breathing mode. These modes are generated during the interaction pulse and persist also after the pulse. The corresponding tunneling dynamics consists of several energy channels accompanying the dynamics. The majority of the tunneling channels persist after the pulse, while only a few occur during the pulse. The induced excitation dynamics is also explored and a strong non-linear dependence on the delayed time of the multipulse protocol is observed. Moreover, the character of the excitation dynamics is also manifested by the periodic population of higher-lying lattice momenta. The above mentioned findings pave the way for future investigations on the direct control of the excitation dynamics. [1] S.I. Mistakidis, L. Cao, and P. Schmelcher, J. Phys. B: At. Mol. and Opt. Phys., 47, 225303 (2014). [2] S.I. Mistakidis, L. Cao, and P. Schmelcher, Phys. Rev. A, 91, 033611 (2015). [Preview Abstract] |
|
Q1.00049: Quantum walks assisted by particle number fluctuations. Rodrigo A Vargas-Hernandez, Roman V Krems We consider quantum walks of particles governed by lattice Hamiltonians with particle-number changing interactions. We show that such interactions, even if weak, accelerate quantum walks at short times due to Rabi oscillations between different particle number subspaces. We examine the dynamics of quantum walks governed by Hamiltonians arising in the context of D-wave quantum annealing experiments and experiments with excitations of ultracold molecules in optical lattices. The same Hamiltonians describe excitations in ensembles of highly magnetic atoms, such as Dy.\\ \\R A Vargas-Hernandez and R V Krems, J. Phys. B: At. Mol. Opt. Phys. 49, 23550 (2016). [Preview Abstract] |
|
Q1.00050: Studying matter-wave emission with ultracold atoms in an optical lattice Arturo Pazmino, Joonhyuk Kwon, Ludwig Krinner, Michael Stewart, Dominik Schneble We report experimental and theoretical progress on the implementation of the Weisskopf-Wigner Hamiltonian in an optical lattice scenario. In our system, lattice-trapped atoms are coupled to a continuum of freely moving, untrapped states via an internal state transition. This fully tunable system allows for studies of a plethora of effects including the transition from Markovian to non-Markovian decay and evanescently bound matter-waves. Recent technological advancements in our labroatory, including the development of a blue-detuned optical lattice and a method to measure magnetic fields to high accuracy, will allow for the exploration of new regimes in these models, especially many-body effects such as superradiant dynamics and extended range (tunneling) Hubbard models. [Preview Abstract] |
|
Q1.00051: Experimental realization of a subwavelength optical potential based on atomic dark state Yang Wang, Sarthak Subhankar, Steven Rolston, James Porto As a well-established tool optical lattice (OL) provides the unique opportunity to exploit the rich manybody physics. However, ''traditional'' OL, either via laser beam interference or direct projection with spatial light modulator, has a length scale around the wavelength (0.1$\sim$10 $\lambda$) that is set by diffraction, a fundamental limit from the wave nature of the light. Recent theoretical proposals \footnote{M. \L{}\k{a}cki \textit{et al}, Phys. Rev. Lett \textbf{117}, 233001 (2016)} \footnote{F. Jendrzejewski \textit{et al.} Phys. Rev. A \textbf{94}, 063422 (2016)} suggest an alternative route, where the geometric potential \footnote{M. Cheneau, \textit{et al.} EPL \textbf{83}, 60001 (2008)}, stemming from light-atom interaction, can be engineered to generate a much finer potential landscape which is essentially limited by the wave nature of the slow moving cold atoms. We report on the progress towards an experimental realization of these ideas using degenerate fermionic ytterbium atoms. Such subwavelength optical potential could open the gate to study physics beyond currently available parameter regimes, such as enhanced super-exchange coupling, magnetic dipolar coupling, and tunnel junction in atomtronics. [Preview Abstract] |
|
Q1.00052: Towards bottom-up assembly of strontium atom arrays Ivaylo Madjarov, Zeren Lin, Alexander Baumgartner, Tyler Jackson, Kevin Chen, Nicholas Redd, Alexandre Cooper, Manuel Endres We report on progress towards controlling single strontium atoms in large, defect-free arrays of optical tweezers. Strontium has both bosonic and fermionic species with narrow optical transitions and magic wavelengths, which enable robust cooling, trapping, and coherent manipulation. By using state of the art light shaping technologies and long vacuum-limited lifetimes, we expect to create defect-free arrays of several hundred atoms. We also explore strategies for sideband cooling and non-destructive imaging in optical dipole traps. [Preview Abstract] |
|
Q1.00053: 1D array of dark spot traps formed by counter-propagating nested Gaussian laser beams for trapping and moving atomic qubits Katharina Gillen-Christandl, Travis D. Frazer The standing wave of two identical counter-propagating Gaussian laser beams constitutes a 1D array of bright spots that can serve as traps for single neutral atoms for quantum information operations [1]. Detuning the frequency of one of the beams causes the array to start moving, effectively forming a conveyor belt for the qubits [1]. Using a pair of nested Gaussian laser beams with different beam waists, however, forms a standing wave with a 1D array of dark spot traps confined in all dimensions [2]. We have computationally explored the trap properties and limitations of this configuration and, trading off trap depth and frequencies with the number of traps and trap photon scattering rates, we determined the laser powers and beam waists needed for useful 1D arrays of dark spot traps for trapping and transporting atomic qubits in neutral atom quantum computing platforms. [1] D. Schrader et al., Appl. Phys. B 73, 819 (2001); [2] P. Zem\'{a}nek, C.J. Foot, Opt. Comm. 146, 119 (1998). [Preview Abstract] |
|
Q1.00054: Superfluid in a shaken optical lattice: quantum critical dynamics and topological defect engineering Anita Gaj, Lei Feng, Logan W. Clark, Cheng Chin We present our recent studies of non-equilibrium dynamics in Bose-Einstein condensates using the shaken optical lattice. By increasing the shaking amplitude we observe a quantum phase transition from an ordinary superfluid to an effectively ferromagnetic superfluid composed of discrete domains with different quasi-momentum. We investigate the critical dynamics during which the domain structure and domain walls emerge. We demonstrate the use of a digital micromirror device to deterministically create desired domain structure. Using this technique we develop a clearer picture of the quantum critical dynamics at early times and its impact on the domain structure long after the transition. [Preview Abstract] |
|
Q1.00055: Quantum many-body dynamics of strongly interacting atom arrays Hannes Bernien, Alexander Keesling, Harry Levine, Sylvain Schwartz, Ahmed Omran, Eric Anschuetz, Manuel Endres, Vladan Vuletic, Markus Greiner, Mikhail Lukin The coherent interaction between large numbers of particles gives rise to fascinating quantum many-body effects and lies at the center of quantum simulations and quantum information processing. The development of systems consisting of many, well-controlled particles with tunable interactions is an outstanding challenge. Here we present a new platform based on large, reconfigurable arrays of individually trapped atoms[1]. Strong interactions between these atoms are enabled by exciting them to Rydberg states. This flexible approach allows access to vastly different regimes with interactions tunable over several orders of magnitude. We study the coherent many-body dynamics in varying array geometries and observe the formation of Rydberg crystals. [1] Science 354, 1024 (2016) [Preview Abstract] |
|
Q1.00056: Observation of quantum thermalization and progress towards the many-body localized regime Adam Kaufman, Eric Tai, Alex Lukin, Matthew Rispoli, Robert Schittko, Tim Menke, Philipp Preiss, Markus Greiner ~In classical thermodynamics entropy plays a crucial role. A classical many-body system equilibrates to a maximally entropic state, and will quickly re-thermalize when perturbed. In contrast, the total entropy of an isolated quantum many-body system does not change following a global or local quantum quench. Nevertheless, sufficiently local observables quickly thermalize to steady state values which are well described by entropic thermal ensembles. Surprisingly, this thermalization is absent in the presence of sufficiently high disorder. In this regime, the system can retain memory of its initial state even at infinite times. We explore these phenomena in a 1D Bose-Hubbard system of ultracold rubidium atoms under a quantum gas microscope. Our microscope gives us unique access to local observables as well as the ability to measure entanglement entropy both locally and globally. We observe a fast growth in subsystems' entanglement entropy after the quench and describe how it provides thermalization for local observables. We have now added disorder to our system to study the breakdown of thermalization in the many-body localized regime; we will present our progress towards these measurements. [Preview Abstract] |
|
Q1.00057: Effective three-body interactions of ultracold bosons in anharmonic traps Philip Johnson, Eite Tiesinga The influence of elastic effective three- and higher-body interactions, induced by virtual excitations of ground-state bosons to excited vibrational states (higher bands in the case of periodic potentials), are seen in a number of experiments with trapped ultracold atoms in optical lattices. One of the most striking signatures, revealed in collapse-and-revival experiments, is a significant modification of the phase dynamics of superfluid bosons. We find, however, a significant deviation between the experimental data for atoms in optical lattices, and theoretical calculations based on harmonic trapping potentials. Using a number of model potentials with varying degrees and types of anharmonicity, we show that effective interaction strengths are highly sensitive to trap shape and anharmonic corrections must be taken into account when analyzing this physics. [Preview Abstract] |
|
Q1.00058: An apparatus for simulating lattice spin models with Rydberg-dressed cesium atoms Ognjen Markovic, Victoria Borish, Jacob Hines, Monika Schleier-Smith Rydberg-dressed atoms provide a versatile platform for engineering lattice spin models for studies of frustrated magnetism and quantum many-body dynamics. We present the design of an experiment that is optimized for achieving highly coherent and dynamically controllable interactions. Cesium atoms will be pinned in a two-dimensional optical lattice of 1-2 $\mu \textrm{m}$ spacing and coupled to the Rydberg manifold with a single ultraviolet photon. A flexible experimental chamber design will permit close optical access for trapping, imaging and addressing, while simultaneously enabling control of the electric field to enhance the strength of interactions or switch their sign. The large interatomic spacing will facilitate single-spin-resolved detection for detailed characterization of many-body quantum states. [Preview Abstract] |
|
Q1.00059: LASER COOLING AND TRAPPING |
|
Q1.00060: Reducing photoassociation and light assisted collisions in tightly confined geometries Alban Urvoy, Jiazhong Hu, Zachary Vendeiro, Wenlan Chen, Vladan Vuletic Light-induced binary loss mechanisms have dramatic consequences for the manipulation of cold atoms with light fields, limiting the performance of optical cooling schemes at high atomic densities, as well as the in-situ observation of atoms in quantum gas microscopes. \\ Here we present our results on several methods for reducing such loss mechanisms for atoms tightly confined in optical lattices. First we show that using light that is far detuned to the red of the atomic transition significantly reduces light-induced binary losses, as predicted by theory. Then we discuss how these loss mechanisms are modified by light scattering effects in low dimension and tightly-confined gases, based on our observation of anomalously low light-induced loss rates. [Preview Abstract] |
|
Q1.00061: Laser cooling and compression of an atomic beam for use in a focused ion beam Steinar H.W. Wouters, Gijs ten Haaf, Tim C.H. de Raadt, Peter H.A. Mutsaers, Edgar J.D. Vredenbregt Magneto-optical compression is performed on a thermal beam of rubidium atoms effusing from a collimated Knudsen source with the aim of generating a high density, low temperature atomic beam that can be ionized into a high brightness ion beam. Such an ion beam can be used in a focused ion beam system (FIB) that is widely used in science and industry to image and modify structures at the nanoscale. Simulations of the proposed setup including the compact magneto-optical compressor, photo-ionization and ion beam focusing have shown that a 1 nm resolution can be achieved, for rubidium at a beam current of 1 pA and 30 keV energy. This will be a mayor improvement over commercial offerings. A collimated Knudsen source for rubidium has been constructed and characterized. The resulting atomic beam is loaded into a compact (70 mm long) magneto-optical compressor (MOC). Behind the MOC sub-Doppler cooling is applied to lower the transverse temperature even further. The resulting beam flux is equivalent to 0.6 nA and the brightness of the beam reads 6$\times$10$^6$ A/m$^2$/sr/eV which is an order of magnitude higher than conventional ion sources promising a higher resolution. This contribution reports about the experimental characterization of the Knudsen source, MOC and sub-Doppler cooler. [Preview Abstract] |
|
Q1.00062: Dipole Trapping under Microgravity Christian Vogt, Marian Woltmann, Sven Herrmann, Claus Lämmerzahl The PRIMUS-Project will be testing the weak equivalence principle (WEP) with a two species (Rb and K) atom interferometer under microgravity. Microgravity offers the benefit of largely extended free evolution times of the atomic ensembles, which significantly enhances the sensitivity. As microgravity platform we chose the drop tower in Bremen, a free fall tower with a height of 110m, which allows for a free fall time of 4,7s and excellent microgravity quality. Contrary to similar projects using an atomic chip (e.g. CAL or QUANTUS), the cold atomic ensembles will be prepared in a dipole trap with a wavelength of about 2\textmu m and a maximum Power of about 10W directly loaded from a 3D-MOT. Dipole Traps have several advantages like a symmetric trap shape and the availability of Feshbach Resonances. They are well established in ground based experiments and will most likely play a major role in space born cold atom experiments. In this manner our project also serves as a pathfinder experiment for further cold atom tests of fundamental physics. Within this work we were just recently able to produce the first dipole trap under microgravity. The talk will be about the current status of the project. [Preview Abstract] |
|
Q1.00063: Achieving Translationally Invariant Trapped Ion Rings Erik Urban, Hao-Kun Li, Crystal Noel, Boerge Hemmerling, Xiang Zhang, Hartmut Haeffner We present the design and implementation of a novel surface ion trap design in a ring configuration. By eliminating the need for wire bonds through the use of electrical vias and using a rotationally invariant electrode configuration, we have realized a trap that is able to trap up to 20 ions in a ring geometry 45um in diameter, 400um above the trap surface. This large trapping height to ring diameter ratio allows for global addressing of the ring with both lasers and electric fields in the chamber, thereby increasing our ability to control the ring as a whole. Applying compensating electric fields, we measure very low tangential trap frequencies (less than 20kHz) corresponding to rotational barriers down to 4mK. This measurement is currently limited by the temperature of the ions but extrapolation indicates the barrier can be reduced much further with more advanced cooling techniques. Finally, we show that we are able to reduce this energy barrier sufficiently such that the ions are able to overcome it either through thermal motion or rotational motion and delocalize over the full extent of the ring. [Preview Abstract] |
|
Q1.00064: Entrainment of lithium atoms into a supersonic beam and magnetic deceleration Yu Lu, Lukas Gradl, Lichung Ha, Logan Hillberry, Kevin Melin, Pavel Nagornykh, Jordan Zesch, Mark Raizen We report our progress on the development of an alternative to laser cooling of neutral atoms, using alkali atoms as the benchmark for a direct comparison. The first step is optimization of entrainment of lithium into a supersonic beam followed by magnetic deceleration. We create a supersonic beam of cold helium gas by pulsing on an Even-Lavie valve, which then crosses lithium vapor generated by a directional oven. The resulting entrainment number and temperature of the lithium atoms are measured downstream with a hot-wire detector. In order to further optimize entrainment, we developed a pulsed atomic source that is synchronized with the supersonic valve with an appropriate delay time. Lithium atoms from the directional oven accumulate on a thin metallic ribbon and are quickly evaporated as a short current pulse is applied, creating a dense plume of lithium vapor. The entrained lithium beam will be slowed by a magnetic decelerator as demonstrated in earlier work, combining all the components to deliver lithium atoms near rest in the laboratory frame. Atomic phase space density will be further increased by a new method that we recently proposed, which utilizes optical pumping and magnetic kicks, and does not rely on the momentum of the photon. [Preview Abstract] |
|
Q1.00065: Narrow-line cooling of neutral Holmium William Milner, Christopher Yip, Donald Booth, Mark Saffman Neutral Holmium’s 128 ground hyperfine states, the most of any non-radioactive element, is a testbed for quantum control of a very high dimensional Hilbert space, and offers a promising platform for quantum computing. Previously we have cooled Holmium atoms in a MOT on a 410.5 nm transition with a Doppler temperature of 780 $\mu$K and characterized its Rydberg spectra. Following these past results, we are currently working towards narrow-line cooling on a 412 nm line with a Doppler temperature of 55 $\mu$K, allowing colder MOT temperatures. We have experimentally determined the excited state hyperfine constants of this transition and will present progress towards cooling on the F = 11 to F' = 12 hyperfine transition of the 412 nm line. [Preview Abstract] |
|
Q1.00066: Toward Measurements With Sympathetically Cooled State-Selected Molecular Ions Ryan A. Carollo, David A. Lane, Alexander Frenett, David Hanneke Deeply bound diatomic molecular ions are of interest for a variety of studies, such as precision measurements, quantum control of rotational states, or quantum memory. We are particularly interested in homonuclear systems, which show promise at suppressing certain systematic effects. We present an apparatus capable of controllably leaking O$_2$, ionizing and sympathetically cooling trapped O$_2^+$, and performing state-selective photoionization. We report on progress toward initial measurements with oxygen, and discuss a proposed precision measurement of the time variation of the proton-to-electron mass ratio using trapped O$_2^+$. [Preview Abstract] |
|
Q1.00067: Progress towards a high temperature inductive oven for an ultracold Er+Na mixture experiment Neil Anderson, Swarnav Banik, Monica Gutierrez, Avinash Kumar, Hector Sosa, Stephen Eckel, Gretchen Campbell One of the major challenges in an ultracold atom experiment is the production of the atomic beam for laser cooling. Atomic species of recent interest such as Er, Dy, Cr present a particular challenge in that they require very high temperatures (upwards of 1000 C) to produce vapor pressures suitable for the generation of a thermal atomic beam. In recent experiments, this challenge has been addressed by using a commercial oven in conjunction with a Zeeman slower. Here we present progress towards an inductive oven for Er. Inductive heating, as opposed to resistive heating, offers the distinct advantage of heating the sample directly, eliminating the need for bulky water cooling stages of conventional high temperature ovens. Additionally, the inductive oven's compact design enables it to serve as a transverse source in a two species 2D MOT setup. [Preview Abstract] |
|
Q1.00068: In situ sensing of position and temperature of a single trapped atom via resonance fluorescence Richard Wagner, Wes Erickson, Dan Steck Temperature measurements of ultra-cold atoms have either required releasing of the atomic cloud or have taken advantage of relatively weak confining forces to observe center-of-mass motion of the cloud. However, tight confinement forces required for single-atom trapping limit temperature measurements to destructive “release-recapture” methods. We present an alternative temperature measurement for single atoms in a MOT. A small oscillation in the magnetic field of a MOT imprints a position-dependent oscillation in the fluorescence of a single atom. Measuring this fluorescence oscillation provides information about the spatial distribution of the atom in the trap, and therefore its temperature. This is done without the need to release the atom, allowing for additional experiments on the atom with a known temperature. [Preview Abstract] |
|
Q1.00069: Towards trapping and laser cooling Ba and La ions Jessie Hankes, Amanda Nelson, Patrick Banner, Steven Olmschenk Trapped atomic ions are one of the leading candidates for applications in quantum information. We are currently working with barium ions (Ba II), directly loaded by laser ablation of a barium titanium oxide target, and laser cooled using visible laser light (650 nm and 494 nm). Motivated by applications of quantum networks, we also present progress towards laser cooling and trapping lanthanum ions (La III), which should enable quantum information protocols at telecom wavelengths for long-distance applications. [Preview Abstract] |
|
Q1.00070: Simulation of a 3D MOT-Optical Molasses Hybrid for Potassium-41 Atoms W. A. Peterson, Jonathan Wrubel We report a design and numerical model for a 3D magneto-optical trap (MOT)-optical molasses hybrid for potassium-41 atoms. In this arrangement, the usual quadrupole magnetic field is replaced by an octupole field. The octupole field has a central region of very low magnetic field where our simulations show that the atoms experience an optical molasses, resulting in sub-doppler cooling not possible in a quadrupole MOT. The simulations also show that the presence of the magneto-optical trapping force at the edge of the cooling beams provides a restoring force which cycles atoms through the molasses region. We plan to use this hybrid trap to directly load a far off-resonance optical dipole trap. Because the atoms are recycled for multiple passes through the molasses, we expect a higher phase-space density of atoms loaded into the dipole trap. Similar hybrid cooling schemes should be relevant for lithium-6 and lithium-7, which also have poorly resolved D2 hyperfine structure. [Preview Abstract] |
|
Q1.00071: Investigation of magic wavelengths for Francium atom with linearly, circularly and elliptically polarized light Sukhjit Singh, Bindiya Arora, B. K. Sahoo Various techniques for laser cooling of atoms have recently become of much interest and are immensely used in modern experiments for carrying out very high precision measurements. In a remarkable work, Katori et. al. in 1999 had explored the use of magic wavelengths ($\lambda_{\rm{magic}}$s) for Sr atoms, at which the investigated transition of the trapped atoms observes null Stark shifts, to reduce the systematics in the measurements. We intend to investigate $\lambda_{\rm{magic}}$s for D1 and D2 lines of Francium(Fr) atom with linearly, circularly and elliptically polarized light. Use of circularly polarized light can be advantageous in increasing the number of $\lambda_{\rm{magic}}$s and using elliptically polarized light can lead to identify $\lambda_{\rm{magic}}$s independent of magnetic sublevels and hyperfine levels. [Preview Abstract] |
|
Q1.00072: Progress toward simultaneous sub-Doppler cooling of $^6$Li and $^7$Li using a single laser frequency Yanping Cai, Daniel Allman, Kevin Wright We have built an experimental system for simultaneous cooling and trapping of $^6$Li and $^7$Li. The cold atomic beam originates from a dual-species 2D MOT with angled effusive sources. Atoms from the 2D MOT are captured in a 3D MOT, and must undergo further cooling for effective loading into a crossed-beam dipole trap. Standard sub-Doppler cooling techniques cannot be used with lithium, however, a Sisyphus cooling technique was recently demonstrated with $^7$Li [1] that uses a single laser frequency at relatively large detuning (several GHz) from the $D$ lines. We have applied this cooling technique to $^6$Li, and measured the cooling efficiency as a function of different parameters including power, detuning, and beam geometry. Because the isotope shift for lithium is only 10 GHz, it should be possible to perform Sisyphus cooling on both isotopes simultaneously with a \emph{single} laser frequency. We will report on progress toward achieving that goal. \newline \noindent$^1$P. Hamilton \textit{et al.}, Phys. Rev. A \textbf{89}, 023409 (2014) [Preview Abstract] |
|
Q1.00073: Apparatus for creating quantum degenerate gas of Lithium-6 Vinod Gaire, Levi Salyards, Cameron Caligan, Colin Parker We describe our apparatus for generation of quantum degenerate gas of lithium-6, a fermion, for further study and simulation of quantum and condensed matter systems. We designed and constructed a modified Bitter type electromagnet and control system which can provide both homogeneous and quadrupole magnetic fields in different current configurations. We are assembling an ultra-high vacuum system for trapping and cooling the lithium atoms and performing experiments. Unique features of the system include an internal radiofrequency antenna and 21-directional optical access to the main chamber. The laser system will be described separately. Progress and a roadmap to degenerate Fermi gases will be outlined. [Preview Abstract] |
|
Q1.00074: Optical bichromatic force deflection of a polyatomic molecule Louis Baum, Ivan Kozyryev, Leland Aldridge, Alex Sedlack, Kyle Matsuda, Edward E. Eyler, John M. Doyle Recently much progress has been made using radiative optical forces for direct laser cooling of diatomic molecules [1]. Our results demonstrating Sisyphus laser cooling of the triatomic free radical SrOH indicate that direct laser cooling is achievable with polyatomic molecules [2]. Moreover, SrOH serves as a test case for techniques that extend to larger molecules (e.g. SrOCH$_3$) [3]. However, spontaneous decay into dark vibrational states remains a pressing challenge, especially as one moves to more complex molecules. The bichromatic force requires fewer spontaneous decays, offers a wide velocity capture range, and promises an order of magnitude enhancement over the saturated radiative force. Recent simulations indicate that the bichromatic force persists in the complicated structure of SrOH [4,5]. We present our progress towards deflection of SrOH with the bichromatic force. We explore the prospects for longitudinal deceleration of molecular beams with an emphasis on utility for direct optical loading of a magnetic trap with complex polyatomic molecules. [1] Gadway et al. J. Phys. B 49 (2016), [2] Kozyryev et al. arXiv:1609.02254 (2016), [3] Kozyryev et al. ChemPhysChem. 17 (2016), [4] Aldridge et al. PRA 93 (2016), [5] Aldridge. PhD Thesis. U. Conn. (2016) [Preview Abstract] |
|
Q1.00075: Development of High Reflector Pellicle Mirrors for Polarized $^{37}$K Beta Decay Asymmetry Studies James McNeil, Alexandre Gorelov, Ben Sheldan, Melissa Anholm, Liam Lawrence, John Behr Precision low energy $\beta$-decay experiments utilize the maximal parity violating standard model property of its charged weak couplings in powerful decay asymmetry studies to probe for new physics up to several TeV in mass scale. The TRIUMF Neutral Atom Trap (TRINAT) investigates the decay asymmetries in optically cooled, polarized $^{37}$K. Following trapping using a magneto-optic trap, optical pumping of $^{37}$K produces highly polarized initial nuclear spin states along the $z$-axis from which $\beta^+$ decay takes place. Thin $12~\mu m$ high reflector pellicle mirrors are developed for our in-vacuum mirror system along the $z$-axis to simultaneously supply circularly polarized light to optically pump the cooled $^{37}$K, while minimizing the MeV $\beta$-scattering and energy loss as it punches through the mirrors before detection. The goal of using the pellicles is to reduce the threshold energy on our event selection to increase statistics at low energy in our $\beta$-asymmetry measurement where possible new physics could exist, while simultaneously improving our momentum resolution. Improved momentum resolution on the $\beta^+$ will aid in constraining our recoil ion detector response function for an eventual measurement of the recoil asymmetry in polarized $^{37}$K. [Preview Abstract] |
|
Q1.00076: Accumulator for Low-Energy Laser-Cooled Particles Kevin Mertes, Peter Walstrom, Michael Di Rosa An accumulator builds phase-space density by use of a non-Hamiltonian process, thereby circumventing Liouville's theorem, which states that phase-space density is preserved in processes governed by Hamilton's equations. We have built an accumulator by a simple magneto-static cusp trap formed from two ring shaped permanent magnets. In traps with a central minimum of $\vert B \vert$, the stored particles are in a field-repelled (FR) Zeeman state, pushed away by $\vert B \vert$ and oscillating about its minimum. After laser-cooling our particles and before entering the trap, we employ the non-hamiltonian process of optical pumping: A FR particle approaches the trap and climbs to the top of the confining potential with a finite velocity. There, it is switched to a field seeking (FS) state. As the switch does not change the velocity, the particle proceeds into the trap but continues to lose momentum because, now in the FS state, the particles sees the decreasing field as a potential hill to climb. Before it comes to a halt, the particle is switched back to a FR state for storage. The process repeats, building the trapped number and density. A simple consideration of potential and kinetic energies would show the trapped particles to have less kinetic energy than those injected. [Preview Abstract] |
|
Q1.00077: Cooling single ions with an optical frequency comb Anthony Ransford, Michael Ip, Xueping Long, Conrad Roman, Andrew Jayich, Wesley Campbell Laser cooled ions have become indispensable tools in a host of atomic clocks and quantum information systems. The vast majority of these ion species, however, have cooling transitions in the UV that are difficult to access with continuous wave (CW) lasers. Mode locked (ML) lasers, due to their high instantaneous intensities, can be frequency multiplied to deep UV efficiently without the need for the complex machinery of CW frequency multiplication systems. While large bandwidth is the hallmark of ML lasers, their spectra also have sufficiently narrow features to make them useful for laser Doppler cooling with performance similar to more complex CW systems. We have demonstrated control of a single 174 Yb$+$ ion's temperature with a frequency doubled optical frequency comb, including single and multiple comb tooth effects, with a scattering rate high enough to rival the performance of CW systems. This work is supported by the US Army Research Office. ~ [Preview Abstract] |
|
Q1.00078: Abstract Withdrawn
|
|
Q1.00079: ULTRACOLD COLLISIONS AND PHOTOASSOCIATION PROCESSES |
|
Q1.00080: Ultracold collisions of Ca + Ca$^+$ Marko Gacesa, Robin C\^ot\'e We report the results of our study of Ca + Ca$^+$ collisions at ultracold temperatures in the presence of a magnetic field. We are primarily interested in characterizing magnetic Feshbach resonances and determine scattering properties of interest for sympathetic cooling of Ca$^+$ ions. Our investigation is based on potential energy curves obtained by recent ab-initio electronic structure calculations that are expected be insufficiently accurate to agree with experiments. We account for this by exploring the dependence of positions and widths of Feshbach resonances on variation of potential energy curves in an effort to determine their shared properties that could be detected at certain magnetic field values. Our study is aimed at guiding future experiments with cold Ca + Ca$^+$ mixtures. [Preview Abstract] |
|
Q1.00081: Geometric phase effects in ultracold hydrogen exchange reactions Balakrishnan Naduvalath, James F. E. Croft, Jisha Hazra, Brian K. Kendrick Electronically non-adiabatic effects play an important role in many chemical reactions. The geometric phase, also known as the Berry's phase, arises from the adiabatic transport of the electronic wave function around a conical intersection between two electronic potential energy surfaces. It is shown that in ultracold collisions of H and D atoms with vibrationally excited HD, inclusion of the geometric phase leads to constructive and destructive interferences between non-reactive and exchange components of the wave function. This results in strong enhancement or suppression of reactivity depending on the final rovibrational levels of the scattered HD molecules. The effect is illustrated for non-rotating and rotationally excited HD molecules in the $v=4$ vibrational level for which the H+HD and D+HD reactions occur through a barrierless path. [Preview Abstract] |
|
Q1.00082: Observation of broad p-wave Feshbach resonances in a 85Rb-87Rb mixture Shen Dong, Yue Cui, Chuyang Shen, YeWei Wu, XiaoBin Ma, Bo Gao, Meng Khoon Tey, Li You We observe new Feshbach resonances in ultracold mixtures of $^{85}$Rb and $^{87}$Rb atoms in the $^{85}$Rb$|2, -2\rangle$+$^{87}$Rb$|1, -1\rangle$ and $^{85}$Rb$|2, +2\rangle$+$^{87}$Rb$|1, +1\rangle$ scattering channels. The positions and properties of the resonances are predicted and characterized using the semi-analytic multichannel quantum-defect theory by Gao [1]. Of particular interest, a number of broad entrance-channel dominated p-wave resonances are identified, implicating exciting opportunities for studying a variety of p-wave interaction dominated physics of superfluid boson mixtures, such as three-body recombination decay and formation of p-wave heteronuclear molecules. \vspace{3ex} \newline [1]Bo Gao, Phys. Rev. A 84, 022706 (2011). [Preview Abstract] |
|
Q1.00083: Reduced dimensional model of ultracold molecule-molecule scattering Christopher Ticknor, Brian Kendrick, Jeff Leiding We study a reduced dimensional molecule-molecule scattering system. This work is an intermediate step in performing the complete scattering calculations as we develop tools to bring together the long range, ultracold 2-body scattering problem and the short range 4-body quantum chemistry problem. We use accurate ab initio electronic calculations to construct the Born Oppenheimer potentials for the nuclear motion. We focus on studying how vibrationally states are excited by the potential. We also present a first set of scattering calculations on these potentials. [Preview Abstract] |
|
Q1.00084: Efimov-van-der-Waals universality for ultracold atoms with positive scattering lengths Jose D'Incao, Paul Mestrom, Jia Wang, Chris Greene We study the universality of the three-body parameters for systems relevant for ultracold quantum gases with positive $s$-wave two-body scattering lengths. Our results account for finite-range van-der-Waals effects and their universality is tested by changing the number of deeply bound diatomic states supported by our interaction model. We find that the physics controlling the values of the three-body parameters associated with the ground and excited Efimov states is constrained by a variational principle and can be strongly affected by $d$-wave interactions that prevent both trimer states from merging into the atom-dimer continuum. Our results enable comparisons to current experimental data and suggest tests of universality for atomic systems with positive scattering lengths. [Preview Abstract] |
|
Q1.00085: Theoretical studies of association and dissociation of Feshbach molecules in a microgravity environment Jose D'Incao, Jason Williams NASA’s Cold Atom Laboratory (CAL) is a multi-user facility scheduled for launch to the ISS in 2017. Our flight experiments with CAL will characterize and mitigate leading-order systematics in dual-atomic-species atom interferometers in microgravity relevant for future fundamental physics missions in space. As part of the initial state preparation for interferometry studies, here, we study the RF association and dissociation of weakly bound heteronuclear Feshbach molecules for expected parameters relevant for the microgravity environment of CAL. This includes temperatures on the pico-Kelvin range and atomic densities as low as $10^8$/cm$^3$. We show that under such conditions, thermal and loss effects can be greatly suppressed, resulting in high efficiency in both association and dissociation of extremely weakly bound Feshbach molecules and allowing for high accuracy determination coherent properties of such processes. In addition we study the possibility to implement delta-kick cooling techniques for weakly bound heteronuclear molecules and explore numerically other methods for molecular association and dissociation including the effects of three-body interactions. [Preview Abstract] |
|
Q1.00086: Coupled square well model and Fano-phase correspondence Bin Yan, Chris Greene This work investigates the Fano-Feshbach resonance with a two-channel coupled-square-well model in both the frequency and time domains. This systems is shown to exhibit Fano lineshape profiles in the energy absorption spectrum. The associated time-dependent dipole response has a phase shift that has recently been understood to be related to the Fano lineshape asymmetric $q$ parameter by $\varphi=2\arg(q-i)$. The present study demonstrates that the phase-$q$ correspondence is general for any Fano resonance in the weak coupling regime, independent of the transition mechanism. [Preview Abstract] |
|
Q1.00087: Universality and chaotic dynamics in reactive scattering of ultracold KRb molecules with K atoms Ming Li, Constantinos Makrides, Alexander Petrov, Svetlana Kotochigova, James F. E. Croft, Naduvalath Balakrishnan, Brian K. Kendrick We study the benchmark reaction between the most-celebrated ultracold polar molecule, KRb, with an ultracold K atom. For the first time we map out an accurate {\it ab initio} ground potential energy surface of the K$_2$Rb complex in full dimensionality and performed a numerically exact quantum-mechanical calculation of reaction dynamics based on coupled-channels approach in hyperspherical coordinates. An analysis of the adiabatic hyperspherical potentials reveals a chaotic distribution for the short-range complex that plays a key role in governing the reaction outcome. The equivalent distribution for a lighter collisional system with a smaller density of states (here the Li$_2$Yb trimer) only shows random behavior. We find an extreme sensitivity of our chaotic system to a small perturbation associated with the weak non-additive three-body potential contribution that does not affect the total reaction rate coefficient but leads to a significant change in the rotational distribution in the product molecule. In both cases the distribution of these rates is random or Poissonian. [Preview Abstract] |
|
Q1.00088: Universal Behavior of Spin Dipolar Relaxation in Atomic Condensates Yuangang Deng, Yiquan Zhou, Min Deng, Qi Liu, Mengkhoon Tey, Bo Gao, Li You The dipolar relaxation of atomic spinor condensates is studied in terms of the semi-analytical scattering wave functions by utilizing the quantum-defect theory. At nonzero magnetic fields, inelastic dipolar relaxation of exothermic reaction leads to loss of the atomic population. By tuning the bias field, we find that the dipolar relaxation rate exhibits a universal behavior involving a unique dip and peak structure, different from the commonly referenced result based on the Born or the distortedwave Born approximations. The positions for the dip and the peak are shown to be determined dominantly by the short-range s-wave scattering length and the Van der Waals radius, independent of the dipolar interaction strength of ultracold atoms. This is confirmed by the precision measured dipolar relaxation decay rate for both spin-polarized atomic coherent spin states and twin-Fock states of $F = 1$ ${}^{\rm{87}}\rm{Rb}$ BoseEinstein condensates. We observe the dipolar relaxation suppression as predicted by our theory for the large bias field, a feature not previously studied experimentally. Our results implicate the possibility of extracting the short-range scattering length and the Van der Waals dispersion coefficient from spin dipolar decay measurements. [Preview Abstract] |
|
Q1.00089: COLD ATOMS, MOLECULES AND PLASMAS |
|
Q1.00090: Diffusion of Single Cs Atoms in a Bath Daniel Mayer, Michael Hohmann, Farina Kindermann, Tobias Lausch, Felix Schmidt, Artur Widera Studying the dynamics of single impurities in a many-body system of ultracold gases allows deducing insights on diffusion processes and non-equilibrium behavior at a microscopic level in a broad parameter range. First, we experimentally observe the non-equilibrium dynamics of single Cs atoms impinging on an ultracold Rb cloud and detect the effect of individual collisions. We render the friction coefficient of a modified Langevin equation velocity dependent and thereby extend the validity range to light impurities which yields excellent agreement with our data without free parameters. We further show that the gas temperature can be retained from the Cs atoms, suggesting their use as local, non-destructive probes for a quantum many-body system. Finally, we couple single Cs atoms in a periodic potential to a bath of near-resonant photons and study the ensuing diffusion. Analyzing diffusion traces of single atoms we observe marked non-Brownian features not detectable in standard ensemble properties and find a surprisingly slow timescale on which ergodicity is established in the system. Our results might shed light on the interpretation of similar phenomena in single-particle tracking experiments in life science. [Preview Abstract] |
|
Q1.00091: Index guiding by optically trapped ultracold atoms measured via optical pumping Jon Gilbert, Jacob Roberts The spatial density variation of optically trapped ultracold atoms is calculated to be sufficient to guide near-resonant red-detuned light through the gas in a manner reminiscent of a graded index fiber for experimentally achievable conditions. We present measurements of light propagating through such an optically trapped gas made via optical pumping by the light. This allows us to measure the light intensity in the gas as a function of propagation distance along the axial direction of the gas in a straightforward fashion. Comparisons between measurements and theoretical expectations based on Maxwell’s equations will be presented. [Preview Abstract] |
|
Q1.00092: Construction of a Quantum Matter Synthesizer Jonathan Trisnadi, Mickey McDonald, Cheng Chin We report progress on the construction of a new platform to manipulate ultracold atoms. The “Quantum Matter Synthesizer (QMS)” will have the capability of deterministically preparing large 2D arrays of atoms with single site addressability. Cesium atoms are first transferred into a science cell (specially textured to reduce reflectance to ~0.1\% across a wide range of wavelengths and incident angles) via a moving 1D lattice, where they are loaded into a magic-wavelength, far-detuned 2D optical lattice. Two NA=0.8 microscope objectives surround the science cell from above and below. The lower objective will be used to project an array of optical tweezers created via a digital micromirror device (DMD) onto the atom-trapping plane, which will be used to rearrange atoms into a desired configuration after first taking a site-resolved fluorescence image of the initial atomic distribution with the upper objective. We provide updates on our magnetic-optical trap and Raman-sideband cooling performance, characterization of the resolution of our microscope objectives, and stability tests for the objective mounting structure. [Preview Abstract] |
|
Q1.00093: Measurements of Collective Mode Frequencies in a Multicomponent Quantum Gas Joshua Hill, James Aman, Thomas Killian The frequencies of collective modes provide a powerful probe of many-body physics in ultracold atom gases. We will describe our characterization of the collective modes in mixtures of atomic species using ultracold strontium, which has a wide assortment of isotopes to work with. A cold thermal-gas of Strontium atoms is prepared in a succession of magneto-optical trap (MOT) stages before being evaporatively cooled in an optical dipole trap (ODT). Additional confinement is then introduced by ramping on a second laser beam, the potential minimum of which is overlapped with the ODT. While maintaining the ODT, the second beam is rapidly turned off, and the gas undergoes collective-mode oscillations. These oscillations are clearly visible in the calculated temperature of the gas after time-of-flight absorption imaging. We identify both center of mass (“sloshing”) and quadrupole modes. [Preview Abstract] |
|
Q1.00094: Optical Phase Coherence in the Adiabatic Rapid Passage (ARP) Force Brian Arnold, Taichi Inaki, Yifan Fang, Harold Metcalf The huge optical force on atoms implemented using ARP results from coherent exchange of momentum between atoms and the light field. This is done with counterpropagating beams of chirped, pulsed light that alternately produce absorption followed by stimulated emission, and has been demonstrated for atoms at rest\footnote{X. Miao, Phys. Rev. A 75, 011402 (2007).}. How does the ARP force depend on atomic velocities $v_a$? Atomic motion in the lab frame corresponds to Doppler-shifted frequencies in the atomic frame, so we use oppositely detuned laser beams to simulate $v_a$. For large $v_a$ this uses two different lasers, but the coherent momentum exchange requires phase locking them\footnote{J. Elgin, Ph.D Thesis, Stony Brook University, 2015.}. This has been implemented and the first results show that the force is nearly constant at low $v_a$ but decreases at higher $v_a$. For an ARP frequency sweep range of $\pm \, \delta_0$, one intuitively expects a range of $v_a$ between 1/4 and 1/2 of $\pm \, \delta_0/k$, and our initial measurements corroborate this. Our new tools enable further exploration of the dependence of the ARP force on $v_a$ as well as the role of phase noise that can be inserted experimentally. [Preview Abstract] |
|
Q1.00095: Efimov Resonances and Quantum Degeneracy in a Strongly Mass-Imbalanced Fermi-Bose Mixture Krutik Patel, B.J. DeSalvo, Jacob Johansen, Cheng Chin We present observations of Efimov resonances in a $^6$Li-$^{133}$Cs mixture near one broad ($s_{res} = 0.71$) and one narrow ($s_{res}=0.02$) interspecies Feshbach resonance near 890 G. These Feshbach resonances have nearly equal intraspecies scattering length, yet we find a substantial difference in the absolute interspecies scattering length at which the Efimov features occur. Our observation confirms the predicted departure from universal physics near the narrow resonance. Additionally, we report the realization of a stable Bose-Einstein condensate of Cs overlapped with a degenerate Fermi gas of Li in a dual color optical dipole trap. Such a system provides a platform for the study of Fermi-Bose quantum mixtures in the ground state with widely tunable interspecies interactions. [Preview Abstract] |
|
Q1.00096: Scale Invariant Quantum Dynamics in Ultracold Jeff Maki, Fei Zhou We examine the effects of scale invariance on the far from equilibrium dynamics of cold atom systems. Such far from equilibrium scale invariant dynamics can be realized in non interacting and unitary Fermi gas in three spatial dimensions. We examine and categorize not only the features of scale invariant far from equilibrium dynamics but the deviations that can arise when one breaks the scale invariance. We show that the long time deviations is related to the beta function of the system, which describes the changes in the correlation length near these two scale invariant points. [Preview Abstract] |
|
Q1.00097: Experiments with bosonic atoms for quantum gas assembly Mark Brown, Yiheng Lin, Brian Lester, Adam Kaufman, Randall Ball, Ludovic Brossard, Leonid Isaev, Tobias Thiele, Robert Lewis-Swan, Kai-Niklas Schymik, Ana Maria Rey, Cindy Regal Quantum gas assembly is a promising platform for preparing and observing neutral atom systems on the single-atom level. We have developed a toolbox that includes ground-state laser cooling, high-fidelity loading techniques, addressable spin control, and dynamic spatial control and coupling of atoms. Already, this platform has enabled us to pursue a number of experiments studying entanglement and interference of pairs of bosonic atoms. We discuss our recent work in probabilistically entangling neutral atoms via interference, measurement, and post-selection as well as our future pursuits of interesting spin-motion dynamics of larger arrays of atoms. [Preview Abstract] |
|
Q1.00098: BOSE-EINSTEIN CONDENSATES |
|
Q1.00099: Dark-bright soliton interactions beyond the integrable limit Garyfallia Katsimiga, Jan Stockhofe, Panagiotis Kevrekidis, Peter Schmelcher In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions, motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. In particular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interaction between two dark-bright solitons in a homogeneous environment beyond the integrable regime, by considering general inter- and intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case where the bright solitons are out of phase. As the intercomponent interaction is increased, we also identify an exponential instability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter gives rise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of the bound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations and monitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis. [Preview Abstract] |
|
Q1.00100: Dark-Bright Soliton Dynamics Beyond the Mean-Field Approximation Garyfallia Katsimiga, Georgios Koutentakis, Simeon Mistakidis, Panagiotis Kevrekidis, Peter Schmelcher The dynamics of dark bright solitons beyond the mean-field approximation is investigated. We first examine the case of a single dark-bright soliton and its oscillations within a parabolic trap. Subsequently, we move to the setting of collisions, comparing the mean-field approximation to that involving multiple orbitals in both the dark and the bright component. Fragmentation is present and significantly affects the dynamics, especially in the case of slower solitons and in that of lower atom numbers. It is shown that the presence of fragmentation allows for bipartite entanglement between the distinguishable species. \% to be also generically observed. Most importantly the interplay between fragmentation and entanglement leads to the decay of each of the initial mean-field dark-bright solitons into fast and slow fragmented dark-bright structures. A variety of excitations including dark-bright solitons in multiple (concurrently populated) orbitals is observed. Dark-antidark states and domain-wall-bright soliton complexes can also be observed to arise spontaneously in the beyond mean-field dynamics. [Preview Abstract] |
|
Q1.00101: Adiabatically tuning quantized supercurrents and superfluid hysteresis in spin-orbit coupled Bose-Einstein condensates Junpeng Hou, Xiwang Luo, Kuei Sun, Chuanwei Zhang The ability to generate and manipulate quantized persistent currents is crucial for building atomtronic devices with novel functionality. Previous schemes for generating quantized supercurrents, such as rotating laser barriers, rely on dynamical process and thus are not accurate and stable. Here we show that arbitrary quantized circulation states can be adiabatically prepared and tuned as the ground state of a BEC confined on a ring by utilizing spin-orbital angular momentum coupling and an external trapping potential. We show that there exists superfluid hysteresis for the process of tuning supercurrents between different quantization values. Our work provides a powerful platform for building and exploring novel superfluid atomtronic circuits. [Preview Abstract] |
|
Q1.00102: Probing many-body physics with a resonantly interacting Bose gas Catherine Klauss, Xin Xie, Carlos Lopez-Abadia, Jose D'Incao, Eric Cornell By sweeping a resonantly interacting Bose-Einstein Condensate (BEC) onto weak interactions, we are able to create a mixture of atoms and molecules. We realize a mixture of free atoms, Feshbach molecules and Efimov molecules, using loss rate measurements to distinguish these components. In particular, the creation of Efimov molecules suggests the presence of three-body correlations in the resonantly interacting BEC, revealing opportunities to study few- and many-body phenomena in a controlled system. We present further investigation into this possibility by studying the overall loss of the resonantly interacting BEC over two orders of magnitude in density. [Preview Abstract] |
|
Q1.00103: Results from the Cold Atom Laboratory's ground test bed Ethan Elliott We describe validation and development of critical technologies in the Cold Atom Laboratory's (CAL) ground test bed, including the demonstration of the first microwave evaporation and generation of dual-species quantum gas mixtures on an atom chip. CAL is a multi-user facility developed by NASA's Jet Propulsion Laboratory (JPL) to provide the first persistent quantum gas platform in the microgravity environment of space. The CAL instrument will be operated aboard the International Space Station (ISS) and utilize a compact atom chip trap loaded from a dual-species magneto optical trap of rubidium and potassium. In the unique environment of microgravity, the confining potentials necessary to the process of cooling atoms can be arbitrarily relaxed, enabling production of gases down to pikoKelvin temperatures and ultra-low densities. Complete removal of the confining potential allows for ultracold clouds that can float virtually fixed relative to the CAL apparatus. This new parameter regime enables ultracold atom research with broad applications in fundamental physics and inertial sensing. [Preview Abstract] |
|
Q1.00104: Progress towards a Na+Er mixture experiment Avinash Kumar, Monica Gutierrez Galan, Neil Anderson, Swarnav Banik, Hector Sosa-Martinez, Stephen Eckel, Ted Jacobson, Ian Spielman, Gretchen Campbell Recent advances in the production of arbitrary trapping potentials for ultracold atoms have enabled the creation and study of analog physical systems using degenerate gases. Here we present an exploration of cosmic inflation realized using a supersonically expanding, toroidally trapped, $^{23}$Na BEC. We observe features of cosmic inflation such as the red-shifting of phonons, particle production, and spontaneous winding number generation. Our group is currently constructing a second-generation experimental apparatus for a Na+Er mixture. This novel setup features a dual species 2D MOT, an improved imaging system, a new locking system for the 583 nm narrow line transition of Er, and high magnetic field capabilities. These new capabilities open the possibility of studying lanthanide-alkali collisions and Feshbach spectra, as well as the realization of other quantum many body systems. [Preview Abstract] |
|
Q1.00105: Dynamics of Bose-Einstein Condensation in Higher Bands Sayan Choudhury, Erich Mueller Motivated by recent experiments, we explore the kinetics of Bose-Einstein condensation in the upper band of a double well optical lattice. These experiments engineer a non-equilibrium situation in which the highest energy state in the band is macroscopically occupied. The system subsequently relaxes and the condensate moves to the lowest energy state. We model this process. We argue that the condensate first evaporates and then recondenses. We explain how this scenario can be verified through future experiments. [Preview Abstract] |
|
Q1.00106: Design of a microgravity shell-geometry Bose-Einstein condensate experiment Nathan Lundblad, Thomas Jarvis, Tiago Correia Notions of geometry, topology, and dimensionality have directed the historical development of quantum-gas physics. Here we review a planned microgravity flight experiment (NASA CAL, launching 2017) which will explore a trapping geometry for quantum gases that is both theoretically tantalizing and difficult to attain terrestrially: a trap forming a spherical or ellipsoidal shell. This trap could confine a Bose-Einstein condensate to the surface of an experimentally-controlled topologically-connected “bubble.” In particular we will review plans for observing shell condensates aboard CAL, and summarize some of the key technical challenges involved. Particular calculations of trap inhomogeneity (resulting in possible incomplete shell coverage) are presented, along with potential mitigation schemes. [Preview Abstract] |
|
Q1.00107: HYBRID QUANTUM SYSTEMS |
|
Q1.00108: A Hybrid Atom-Superconductor Interface for Quantum Networking Remy Legaie, Craig Picken, Jonathan Pritchard Quantum mechanics offers a revolutionary approach to how information is processed, with unprecedented levels of security through quantum encryption and exponential speed up with quantum computing. A key challenge to exploiting these benefits is the development of the next-generation hardware required for creating networks exploiting light at the single photon level. Hybrid quantum computation overcomes this challenge by combining the unique strengths of disparate quantum technologies, enabling realization of a scalable quantum devices. \\ We present a new project using cold atoms trapped above superconducting microwave resonators to enable generation, storage and entanglement of optical photons on-chip. Strong Rydberg atom dipole-dipole interactions provide a mechanism for efficient single photon coupling to atomic ensembles, whilst entanglement is mediated via an off-resonant interaction with the superconducting microwave cavity to provide long distance ($\sim$mm scale) interaction lengths. This represents the first steps to the creation of a quantum analog of a router, an essential building block for quantum networking. Long term this can be integrated with superconducting qubits technologies to exploit fast on-chip processing power. [Preview Abstract] |
|
Q1.00109: Rydberg Atom Quantum Hybrid Systems Yuanxi Chao, Jiteng Sheng, Santosh Kumar, Nicholas P. Bigelow, James P. Shaffer We report on our recent experimental and theoretical work with Rydberg atom-cavity and Rydberg atom-surface hybrid quantum systems. In the atom-cavity system, Rb contained in a dipole trap is transported into a high-finesse optical cavity using a focus-tunable lens. Cavity assisted Rydberg EIT is observed in the cavity transmission and used to characterize the electric fields in the cavity. The electric fields are attributed to surface adsorbates adhering to the cavity mirrors. We also investigate the coupling of a Rydberg atom ensemble to surface phonon polaritons (SPhPs) propagating on piezoelectric superlattices made from thin film ferroelectric materials. Strong coupling between the atomic and surface excitations can be achieved, due to the large Rydberg transition dipole moments and the local field enhancement of the SPhP modes. The system has many advantages for information transport since the atoms need only be placed at distances on the order of mms from the surface and the SPhPs do not couple to free space electro-magnetic fields. Experimental progress will be discussed, including the fabrication of submicron-period periodically poled Lithium Niobate using the direct e-beam writing technique. [Preview Abstract] |
|
Q1.00110: Photonic and Phononic Entanglement with Hybrid Species Ion Chains Clayton Crocker, Martin Lichtman, Ksenia Sosnova, Tuan Nguyen, Allison Carter, Volkan Inlek, Hanna Ruth, Christopher Monroe Trapped atomic ions represent a leading platform for quantum information networks due to their long coherence times and diverse set of entangling operations. External fields can drive strong local entangling interactions via phonons, and remote qubits can be entangled via emitted photons. Unfortunately, resonant light from the photonic entanglement process can disrupt nearby memory qubits. We resolve this crosstalk by introducing a separate atomic species to the trap for use as a photonic entanglement qubit. We report successful demonstration of both entangling gates between the mixed species qubit pair through their collective motion, and entanglement between our remote entanglement qubit and emitted visible photons. We additionally report our progress on a new trapping apparatus that was implemented to improve these operations to a level required for scaling up the system size. [Preview Abstract] |
|
Q1.00111: Spin-mediated optomechanics : A hybrid quantum system for quantum sensing and transduction Hil F H Cheung, Yogesh S Patil, Jialun Luo, Mukund Vengalattore We describe our realization of a hybrid quantum system consisting of a mesoscopic mechanical resonator optically interfaced to an ultracold spin ensemble. Combining ultrahigh quality factor resonators with the strong optical interactions and low decoherence rates of the ultracold gas, we show that the parameters of our system ensure the operation of this hybrid quantum system in the strong coupling regime. We demonstrate that the optical coupling between the resonator and the quantum spins realizes a powerful 'spin-photon-phonon' interface for applications to quantum sensing and quantum state preparation. Furthermore, we show that the ultracold spin ensemble can enhance and dynamically tune the optomechanical coupling to create effective nonlinear interactions between the resonator and the quantum spins. [Preview Abstract] |
|
Q1.00112: A novel nanophotonic platform for optomechanics in the strong coupling regime Aditya G Date, M M Torunbalci, Jialun Luo, Claire Warner, Hil F H Cheung, Yogesh S Patil, Sunil Bhave, Mukund Vengalattore We describe the realization of a novel microtoroidal resonator for optomechanics in the strong coupling regime. Owing to its design and material properties, the microresonator exhibits low mechanical and optical dissipation leading to strong interactions between its mechanical and optical whispering gallery modes. In addition to the conventional optomechanical control via a nanofiber interface, this device also enables the strong coupling between nanomechanical motion and the collective spin of an ultracold atomic gas. We describe the fabrication and characterization of this device and discuss prospects of beyond-SQL rotation sensing and optical synchronization of the resonator to a microwave transition of the ultracold gas. [Preview Abstract] |
|
Q1.00113: Towards Long Range Spin-Spin Interactions via Mechanical Resonators Jan Gieseler, Arthur Safira, Aaron Kabcenell, Jack Harris, Mikhail Lukin Nitrogen vacancy centers (NVs) are promising candidates for quantum computation, with room temperature optical spin read-out and initialization, microwave manipulability, and weak coupling to the environment resulting in long spin coherence times. The major outstanding challenge involves engineering coherent interactions between the spin states of spatially separated NV centers. To address this challenge, we are working towards the experimental realization of mechanical spin transducers. We have successfully fabricated magnetized high quality factor (Q\textgreater 10$^{\mathrm{5}})$, doubly-clamped silicon nitride mechanical resonators integrated close to a diamond surface, and report on experimental progress towards achieving the coherent coupling of the motion of these resonators with the electronic spin states of individual NV centers under cryogenic conditions. Such a system is expected to provide a scalable platform for mediating effective interactions between isolated spin qubits. [Preview Abstract] |
|
Q1.00114: Nanophotonic cavity QED with individually trapped atoms Tamara Dordevic, Polnop Samutpraphoot, Hannes Bernien, Paloma Ocola, Sylvain Schwartz, Vladan Vuletic, Crystal Senko, Mikhail Lukin The realization of strong interactions between single photons and single atoms is a central theme in quantum optics and an essential prerequisite for future quantum applications such as quantum networks. We achieve such interactions by using a hybrid approach in which we couple individually trapped atoms to nanophotonic crystal cavities [1]. Here we present our methods for trapping and cooling two atoms near a nanophotonic cavity and our progress towards preparing an entangled state of two atoms mediated by the cavity photons. Our experiment aims at demonstrating scalable and efficient quantum gates [2] with applications in integrated quantum networks. [1] J. D. Thompson, T. G. Tiecke, N. P. de Leon, J. Feist, A. V. Akimov, M. Gullans, A. S. Zibrov, V. Vuletić, and M. D. Lukin, Science 340, 1202 (2013) [2] T. G. Tiecke, J. D. Thompson, N. P. de Leon, L. R. Liu, V. Vuletic and M. D. Lukin, Nature 508, 241 (2014) [Preview Abstract] |
|
Q1.00115: Exploring photon-mediated long-range interaction in a cold atom array trapped on a nanophotonic resonator May Kim, Tzu-Han Chang, Brian Fields, Chen-Lung Hung Recent experimental demonstrations of trapped atoms near nanoscale photonic waveguides and cavities have proven that such hybrid platforms can offer unprecedentedly strong radiative coupling between single atoms and single photons, capable of mediating long-range interactions between atomic pseudo spins. It opens up the possibility to further engineer long-range quantum spin models that is otherwise difficult to achieve in cold atom experiments. In addition, with the coherent long-range atom-atom interactions mediated by photons with intermediate to high cooperativity, we can explore novel physics arising from few to many-photon induced self-organization. We expect rich physics arising from strong coupling between the atomic and photonic fields, which cannot be described by simple mean-field theory. We report on the design and experimental progress toward realizing such a novel system, using laser cooled cesium atoms localized near the surface of a high quality nanophotonic resonator, and discuss our schemes to control atom-atom interactions as well as ways to probe the resulting quantum states. [Preview Abstract] |
|
Q1.00116: Radiation enhanced antiferromagnetic exchange between spins in a superconducting host Kamphol Akkaravarawong, Jukka Vayrynen, Jay Sau, Leonid Glazman, Norman Yao A magnetic impurity on a conventional superconductor can host a localized bound state whose energy lies inside the superconducting gap. If the distance between two such impurities is smaller than the coherence length, the presence of these so-called Yu-Shiba-Rusinov (YSR) bound states can induce an antiferromagnetic exchange interaction between the impurities, falling off as $1/r^2$. Although the YSR interaction exhibits a slower decay than conventional RKKY interactions, its strength is significantly weaker, making it extremely challenging to experimentally observe. We demonstrate that the strength of the YSR interaction can be enhanced via radiation assisted virtual occupation, and that the signature of this coupling can naturally be observed through spectroscopy. [Preview Abstract] |
|
Q1.00117: New Diamond Color Center for Quantum Communication Ding Huang, Brendon Rose, Alexei Tyryshkin, Sorawis Sangtawesin, Srikanth Srinivasan, Daniel Twitchen, Matthew Markham, Andrew Edmonds, Adam Gali, Alastair Stacey, Wuyi Wang, Ulrika D’Haenens-Johansson, Alexandre Zaitsev, Stephen Lyon, Nathalie de Leon Color centers in diamond are attractive for quantum communication applications because of their long electron spin coherence times and efficient optical transitions. Previous demonstrations of color centers as solid-state spin qubits were primarily focused on centers that exhibit either long coherence times or highly efficient optical interfaces. Recently, we developed a method to stabilize the neutral charge state of silicon-vacancy center in diamond ($SiV^0$) with high conversion efficiency. We observe spin relaxation times exceeding 1 minute and spin coherence times of $1 ms$ for $SiV^0$ centers. Additionally, the $SiV^0$ center also has $>90\%$ of its emission into its zero-phonon line and a narrow inhomogeneous optical linewidth. The combination of a long spin coherence time and efficient optical interface make the $SiV^0$ center a promising candidate for applications in long distance quantum communication. [Preview Abstract] |
|
Q1.00118: Strongly Interacting mm-Wave and Optical Photons with Rydberg Atoms Mark Stone, Aziza Suleymanzade, Scott Eustice, Jonathan Simon, David Schuster We describe progress towards a hybrid experimental system for engineering strong interactions between single optical and mm-wave photons using Rydberg atoms as an interface. Entanglement between photons with gigahertz and optical frequencies creates a new platform to access exotic photonic quantum states as well as powerful new techniques in quantum computing and simulation. We will present recent experimental developments including trapping and cooling atoms in a cryogenic MOT, measuring high-Q superconducting cavities at 100 GHz and coupling atoms to an optical cavity inside a cryostat at 3 Kelvin. [Preview Abstract] |
|
Q1.00119: MATTER WAVE INTERFEROMETRY |
|
Q1.00120: Measuring the fine structure constant with Bragg diffraction and Bloch oscillations\\ Weicheng Zhong, Richard Parker, Chenghui Yu, Brian Estey, Holger M{\"u}ller \\We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations. In this new scheme, we have achieved a resolution of $\delta\alpha/\alpha=0.25ppb$ in the fine structure constant measurement, which gives over 10 million radians of phase difference between freely evolving matter waves. We have suppressed many systematic effects known in most atom interferometers with Raman beam splitters such as light shift, Zeeman effect shift as well as vibration. We have also simulated multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implemented spatial filtering to further suppress systematic. [Preview Abstract] |
|
Q1.00121: Spatial variation of interference fringes in a cold atom Sagnac interferometer based on a single large Raman beam Sangkyung Lee, Tae Hyun Kim, Sin Hyuk Yim, Kyu Min Shim We have developed a cold atom Sagnac interferometer where a $\pi $/2$-\pi -\pi $/2 Raman pulse sequence is realized by a single large Raman beam. Because the launched atomic cloud is crossing the Raman beam along the radial direction, the sides of the atomic cloud do not satisfy the $\pi $/2 pulse condition and that leads the variation in spatial contrast in the atomic cloud. The time-of-flight measurement performed by the thin probe beams, whose widths are 4 times smaller than the size of the atomic cloud enables analysis of the variation in spatial contrast. We analyzed the contrast as a function of the radial positions and the widths of the spatial selection. With a help of the spatial selection, we achieved the 1.3 times contrast enhancement with respect to the fully integrated contrast. We also discuss the effect of the spatial selection in the angular sensitivity. [Preview Abstract] |
|
Q1.00122: Surface-sensitive molecular interferometry: beyond {}$^3$He spin echo experiments Joshua T Cantin, Roman V Krems, Oded Godsi, Tsofar Maniv, Gil Alexandrowicz {}$^3$He atoms can be used as surface-sensitive atomic interferometers in {}$^3$He spin echo experiments to measure surface morphology, molecular and atomic surface diffusion dynamics, and surface vibrations. However, using the hyperfine states of molecules gives experiments the potential to be less expensive, be more sensitive, and include angle-dependent interactions. The manifold of hyperfine states of molecules is large in comparison to the two nuclear spin states used in {}$^3$He spin echo experiments and allows for increased precision, while simultaneously complicating experimental interpretation. Here, we present the theoretical formulation required to interpret these experiments. In particular, we show how to determine the effect of magnetic lensing on the molecular hyperfine states and use a modified form of the transfer matrix method to quantum mechanically describe molecular propagation throughout the experiment. We also discuss how to determine the scattering matrix from the experimental observables via machine learning techniques. As an example, we perform numerical calculations using nine hyperfine states of \emph{ortho}-hydrogen and compare the results to experiment. [Preview Abstract] |
|
Q1.00123: Continuous Rotation and Acceleration Sensing in a Dual Atom Interferometer Frank Narducci, Mary Locke, Raghav Simha, Jon Davis, Aaron Meldrum, George Welch The theoretical model and progress of achieving pure acceleration and rotation measurements using atom interferometry is presented. We source our interferometer with a high flux (10$^{\mathrm{8}}$ 1/s) atom beam derived from a 2D MOT without the use of co-propagating optical beams. With the aim of circumventing complications and measurement discontinuities arising from pulsed Raman fields, we utilize continuous Raman fields with the transverse velocity of the atom beam determining our $\pi $/2-$\pi $-$\pi $/2 ``pulse'' condition. Along with the sensitivity benefits of matter wave interferometry as compared to optical interferometry, the continuous nature of our apparatus makes it beneficial for inertial navigation. [Preview Abstract] |
|
Q1.00124: Implementing large momentum transfer in an Ytterbium BEC contrast interferometer for photon recoil and $\alpha$. Daniel Gochnauer, Benjamin Plotkin-Swing, Katie McAlpine, Subhadeep Gupta We operate an ytterbium (Yb) Bose-Einstein condensate (BEC) contrast interferometer designed to make a precision measurement of the fine structure constant, $\alpha$, via a measurement of h/m, where h is Planck’s constant and m is the mass of Yb [1]. Our interferometer is insensitive to both magnetic fields, due to the electronic structure of bosonic Yb, and physical vibrations, due to the symmetry of the interferometer geometry. In this geometry the total phase accumulation and therefore measurement sensitivity scales as N$^{2}$, where N is the number of photon pairs which accelerate one of the interfering paths. We have observed contrast interferometer fringes after imparting 2N$\hbar$k momentum from photon recoils for N$>$1. We have also separately demonstrated Yb BEC acceleration by up to 200$\hbar$k by using Bloch oscillations. The laser pulses for these atom-optics are precisely controlled with analog intensity stabilization and direct digital synthesis generation of frequencies. We are working on implementing acceleration to high N values within the interferometer, and will report on our work towards demonstrating quadratic increase with recoil number in the total phase accumulation and thus interferometer sensitivity. [1] A. Jamison et. al, Phys. Rev. A 90, 063606 (2014) [Preview Abstract] |
|
Q1.00125: TIME-RESOLVED ELECTRON DYNAMICS AND ATTOSECOND SPECTROSCOPY |
|
Q1.00126: Time-dependent local density approximation study of iodine photoionization delay. Maia Magrakvelidze, Himadri Chakraborty We investigate dipole quantum phases and Wigner-Smith (WS) time delays in the photoionization of iodine using Kohn-Sham time-dependent local density approximation (TDLDA) [1] with the Leeuwen and Baerends exchange-correlation functional [2]. Study of the effects of electron correlations on the absolute as well as relative delays in emissions from both valence 5p and 5s, and core 4d, 4p and 4s levels has been carried out. Particular emphasis is paid to unravel the role of correlations to induce structures in the delay as a function of energy at resonances and Cooper minima. The results should encourage attosecond measurements of iodine photoemission and probe the WS-temporal landscape of an open-shell atomic system. [1] Magrakvelidze et al, Phys. Rev. A 91, 063415 (2015). [2] van Leeuwen et al, Phys. Rev. A 49, 2421 (1994). [Preview Abstract] |
|
Q1.00127: Attosecond relative delay among xenon 5p, 5s, and 4d photoionization. Maia Magrakvelidze, Mohamed Madjet, Himadri Chakraborty Attosecond Wigner-Smith (WS) time delays of the photoemissions of Xe valence 5p, 5s, and core 4d electrons are investigated in details using the time-dependent local density approximation (TDLDA) [1]. Electron correlations determine the energy-dependent structures in ionization phases of the dipole channels and in the resulting WS delays at various shape resonances, induced by the collective motion of 4d electrons, and at various Cooper minima. We find that our calculation closely agrees with the streaking measurement [2] for the delay of 4d relative to 5s, and predicts accelerated emission of 5p with respect to 4d as was experimentally observed [3] at similar photon energies for Xe atoms adsorbed on the tungsten surface [4]. [1] Magrakvelidze et al, Phys. Rev. A 91, 063415 (2015). [2] Magrakvelidze et al, Phys. Rev. A 94, 013429 (2016). [3] Verhoef et al, CLEO:OSA Tech. Digest QF2C.4 (2013). [4] Neppl, Ph.D. Thesis, Tech. U Munich (2012). [Preview Abstract] |
|
Q1.00128: Attosecond coherence control of Helium ions ensemble Saad Mehmood, Eva Lindroth, Luca Argenti Attosecond extreme ultraviolet (XUV) pulses trigger the release of a photoelectron from an atom or molecule in a coherent ionization process. As soon as the electron is emitted, however, part of the coherence in the residual parent-ion is lost, and so is the chance of guiding any subsequent transformations of the target in a reproducible way. To influence the parent-ion coherence, the system must be perturbed with additional light pulses before the ionization process is over. Here we present a theoretical study of the attosecond XUV-pump IR-probe ionization of the Helium atom to the 2s and 2p $He^{+}$ states. In electrostatic approximation, these states are degenerate, and hence their coherent superposition gives rise to a parent ion with a permanent dipole moment. We show that the magnitude of the polarization can be controlled by altering the time delay between the XUV and IR pulses on a timescale of few femtoseconds, which is comparable to the beating between the autoionizing states populated by the XUV pulse. Furthermore, on a timescale of few picosecond, the dipole moment fluctuates even in absence of external fields, due to spin orbit interaction. Our results show how the slow dynamics of such polarized-ion ensemble can be controlled with attosecond precision. [Preview Abstract] |
|
Q1.00129: Attosecond time-resolved photoemision from Ag(111) and Au(111) Marcelo Ambrosio, Uwe Thumm Motivated by very recent time-resolved photoemission experiments from solid surfaces using the RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) method [1,2], we calculated RABBITT spectra from Ag(111) and Au(111) surfaces. In this contribution we focus on the modeling of the unperturbed valence electronic structure and compare numerical results obtained by representing the d-valence band of the target by either eigenstates of a parameterized effective potential (``Chulkov potential'') [3] or tight-binding states [4]. We find RABBITT specta based on tight-binding initial states to be in better agreement with the experimental spectra in Ref. [1]. We further find it necessary to include -- through an appropriate modification of field-dressed free-electron (Volkov) states - the Fresnel transmission and reflection of the streaking IR-laser pulse at the vacuum-solid interface [5]. [1] R. Locher \textit{et al.} Optica \textbf{2}, 405 (2015). [2] Z. Tao \textit{et al.} Science \textbf{353}, 62 (2016). [3] E. Chulkov, V. Silkin, and P. Echenique, Surf. Sci. 437, 330 (1999). [4] C. H. Zhang and U. Thumm, Phys. Rev. A \textbf{80}, 032902 (2009) [5] M. J. Ambrosio and U. Thumm, A \textbf{94}, 063424 (2016). [Preview Abstract] |
|
Q1.00130: Theoretical study of imaging the plasmonic field enhancement on the surface of the gold nanosphere by using attosecond streaking spectroscopy Erfan Saydanzad, Jianxiong Li, Uwe Thumm Attosecond time-resolved spectroscopy has been shown to be a powerful method for investigating the electronic dynamics in atoms, and this technique is now being transferred to the investigation of electronic excitations, electron propagation, and collective electronic (plasmonic) effects in near solid surfaces [1,2] and nanoparticles [1,3]. By sampling over classical photoelectron trajectories, we simulated IR-streaked XUV-photoemission spectra for gold nanospheres of 5 and 50 nm radius. Based on our numerical results, we show how spatio-temporal information of the sub-infrared-cycle plasmonic and electronic dynamics is embedded in streaked spectra. [1] U. Thumm, Q. Liao, E. M. Bothschafter, F. S\"{u}{\ss}mann, M. F. Kling, and R. Kienberger, p. 387, Handbook of Photonics, Vol. 1, (Wiley 2015) [2] Q. Liao and U. Thumm, Phys. Rev. A 92, 031401(R) (2015). [3] J. Li, E. Saydanzad, and Uwe Thumm, Phys. Rev. A 94, 051401(R) (2016). [Preview Abstract] |
|
Q1.00131: Streaked photoemission from polycrystalline gold Marcelo Ambrosio, Uwe Thumm We present and analyze IR streaked photoemission spectra [1] from a polycrystalline gold surface for XUV photon energies of 20 and 93 eV. We compare simulated spectra representing the valence electronic structure of the surface in either jellium approximation or based on LDA calculations [2] for IR pulses with 10$^{\mathrm{10}}$ and 10$^{\mathrm{11}}$ Watt/cm$^{\mathrm{2}}$ intensity. Our simulated spectra depend strongly on the IR skin depth and assumed reflection mode (perfect absorption, perfect transmission, perfect reflection, and Fresnel reflection). [1] Q. Liao and U. Thumm, Phys. Rev. A 92, 031401 (2015). [2] E. Chulkov, V. Silkin, and P. Echenique, Surf. Sci. 437, 330 (1999). [Preview Abstract] |
|
Q1.00132: Modeling fast photoemission from GaAs Evan Brunkow, Nathan Clayburn, Maria Becker, Eric Jones, Herman Batelaan, Timothy Gay We present a model that enables us to determine if multi-photon electron photoemission is ``fast,'' i.e., has a time duration comparable to the laser pulses that produce it. In femtosecond pump-probe experiments performed at 775 nm and 100 MHz, laser-induced field emission of electrons from metallic nanotips is considered fast when the emission process is nonlinear in intensity and additive. This means that the emission rate from the source with both pulses present is equal to the sum of the emission rates generated from the pump and probe pulses alone at sufficient delays. [1]. For a GaAs tip source, the emission is instead sub-additive for delays less than a nanosecond, meaning that the emission rate with both pulses present is less than the sum of the pump and probe beams alone [2]. Our model and preliminary data supports the conclusion that the emission from GaAs is fast, and we conclude any material with a non-linear emission process and sub-additivity also has fast emission. This model predicts that the presence of electrons in the conduction band of GaAs causes a decrease in emission due to the second laser pulse. [1] B. Barwick \textit{et al.}, New J. Phys., 9, 142 [2] E. Brunkow \textit{et al.}, B.A.P.S., 61, No. 8, 53 [Preview Abstract] |
|
Q1.00133: Energy-dependent phases more fundamental than ``attosecond time delays" Greg Armstrong, B. D. Esry The time delay in photoemission from neighboring atomic valence sub-shells has become an area of considerable recent interest, with delays of tens of attoseconds reported in experiments for a number of atomic targets.The assumption that such delays are particular to electronic dynamics is questionable, given our recent calculation of ``attosecond delays" in nuclear motion. Moreover, in both cases, the connection of such delays to physical delays in wavepacket creation or detection is inherently ambiguous, for example, due to gauge-dependence. Previous atomic studies using the RABBIT technique have extracted time delays from phase differences in the energy spectra for different sub-shells as a function of delay between harmonics. We will argue, however, that the more fundamental physical information lies in the energy dependence, which may be related to quantities such as the scattering phase shift. A molecular target such as HeH$^+$ provides a convenient analog of atomic systems, allowing the investigation of energy-dependent phases in dissociation from adjacent vibrational states. Using a RABITT-like combination of laser pulses, and applying the photon-phase formalism, we extract information on energy-dependent phases and their relation to scattering phase shifts. [Preview Abstract] |
|
Q1.00134: Ultrafast laser control of autoionizing resonances observed in attosecond transient absorption Chen-Ting Liao, Nathan Harkema, Arvinder Sandhu Attosecond and femtosecond extreme ultraviolet (XUV) pulses can be used to probe electron dynamics in high-lying excited states that autoionize on a femtosecond timescale, thus providing information on the process of Auger decay and its interference with the continua. Here we utilize XUV pulses in connection with infrared (IR) pulses to perform attosecond transient absorption spectroscopy of the impulsive response of argon autoionizing Rydberg states in the vicinity of the $3s^{-1}4p$ resonance. We show that by tuning the time delay and field polarization of IR pulse, it is possible to control the dipolar coupling between neighboring states and hence the spectral line shape of the resonance, such as the transition between Breit-Wigner to Beutler-Fano profiles. [Preview Abstract] |
|
Q1.00135: Analytical model for atomic resonant attosecond transient absorption C Cariker, T Kjellson, E Lindroth, L Argenti Recent advancements in ultrafast laser technology have made it possible to probe electron dynamics in highly excited atomic states that autoionize on a femtosecond timescale, thus giving insight into the dynamics of Auger decay and its interference with the continuum. These experiments provide a stringent test for time-resolved analytical models of autoionization. Here we present a finite-pulse, multi-photon perturbative model which is used in conjunction with ab-initio structure calculations to predict the attosecond transient absorption spectrum (ATAS) of an atom above the ionization threshold. We apply this model to compute the ATAS of argon in the vicinity of the $3s^{-1}4p$ resonance as a function of the time delay between an extreme ultraviolet (XUV) and an infrared (IR) pulse, as well as of the angle between their polarization. We show that by modulating the parameters of the IR pulse it is possible to control the dipolar coupling between neighboring states and hence the lineshape of the $3s^{-1}4p$ resonance. [Preview Abstract] |
|
Q1.00136: Relativistic effects in photoionization: Wigner time delay for the noble gases and IIB atoms Sourav Banerjee, Pranawa Deshmukh, Valeriy Dolmatov, Anatoli Kheifets, Steven Manson Time delay in atomic photoionization has been observed in several experiments [1, 2], and various theoretical and experimental approaches are developing rapidly to obtain a better understanding of this phenomena [3]. Theoretical methods that account for many body correlations include the relativistic random phase approximation (RRPA) [4] and its non-relativistic analogue, RPAE [5]. Calculations using RRPA are performed and the impact of relativistic interactions on Wigner time delay are explored \textit{via} comparison of this result with RPAE results [6, 7]. In addition, results on Wigner time delay for Zn Cd and Hg are presented. [1] M Schultze \textit{et al}, \textit{Science} \textbf{328}, 1658 (2010). [2] K Kl\"{u}nder \textit{et al, PRL} \textbf{106}, 143002 (2011). [3] \quad R. Pazourek, \textit{et al}, Rev. Mod. Phys. \textbf{87}, 765 (2015) [4] W. R. Johnson, C. D. Lin, \textit{Phys. Rev. A} \textbf{20,} 964 (1979) [5] M.Y.Amusia, \textit{Atomic Photoeffect} (Plenum Press, New York, 1990). [6] A. S. Kheifets, Phys. Rev. A \textbf{87}, 063404 (2013). [7] A. Kheifets \textit{et al}, Phys. Rev. A \textbf{94}, 013423 (2016). [Preview Abstract] |
|
Q1.00137: Wigner time delay in photodetachment of Tm\$^{\mathrm{\mathbf{-}}}$and in photoionization of Yb: A comparative study. Soumyajit Saha, Jobin Jose, Pranawa Deshmukh, Valeriy Dolmatov, Anatoli Kheifets, Steven Manson Preliminary studies of Wigner time delay [1] in photodetachment spectra of negative ions have been reported [2]. Photodetachment time delay for some dipole channels of Tm$^{\mathrm{-}}$ and of Cl$^{\mathrm{-}}$ were calculated using relativistic random phase approximation (RRPA) [3,4]. Comparisons between photodetachment time delay of Cl$^{\mathrm{-}}$ and photoionization time delay of Ar were made. We investigate the photodetachment time delay for all three relativistically split nd$\to \varepsilon $f channels of Tm$^{\mathrm{-\thinspace }}$and for nd$\to \varepsilon $f channels of Yb (isoelectronic to Tm$^{\mathrm{-}})$ using RRPA. We study the effect of the shape resonance, brought about by the centrifugal barrier potential [5], on photodetachment time delay. A negative ion is a good laboratory for studying the effects of shape resonances on time delay since the phase is unaffected by the Coulomb component. [1] E. P. Wigner, \textit{Phys. Rev.} \textbf{98,} 145 (1955) [2] S. Saha, \textit{et al}, \textit{BAPS }\textbf{61}(8), 53 (2016) \quad [3] W. R. Johnson, C. D. Lin, \textit{Phys. Rev. A} \textbf{20,} 964 (1979) [4] W. R. Johnson, \textit{et al}, \textit{Phys. Rev. A} \textbf{25,} 337 (1982) [5] A. R. P. Rau and U. Fano, \textit{Phys. Rev.} \textbf{167,} 7 (1968). [Preview Abstract] |
|
Q1.00138: Angular dependence of EWS time delay for photoionization of @Xe Ankur Mandal, Pranawa Deshmukh, Anatoli Kheifets, Valeriy Dolmatov, Steven Manson Interference between photoionization channels leads to angular dependence in photoionization time delay [1, 2]. Angular dependence is found to be a common effect for two-photon absorption experiments very recently [3]. The effect of confinement on the time delay [4, 5] where each partial wave contributions to the ionization are studied. In this work we report angular dependence and confinement effects on Eisenbud-Wigner-Smith (EWS) time delay in atomic photoionization. Using [6] and [1] we computed the EWS time delay for free and confined Xe atom for photoionization from inner 4d$_{\mathrm{3/2}}$ and 4d$_{\mathrm{5/2}}$ and outer 5p$_{\mathrm{1/2}}$ and 5p$_{\mathrm{3/2}}$ subshells at various angles. The calculated EWS time delay is few tens to few hundreds of attoseconds (10$^{\mathrm{-18}}$ second). The photoionization time delay for @Xe follows that in the free Xe atom on which the confinement oscillations are built. The present work reveals the effect of confinement on the photoionization time delay at different angles between photoelectron ejection and the photon polarization. [1] A. Kheifets et al, Phys. Rev. A \textbf{94} 013423 (2016); [2] J. W\"{a}tzel, et al, J. Phys. B \textbf{48}, 2: 025602 (2014); [3] S. Heuser et al. Phys. Rev. A \textbf{94} 063409 (2016); [4] P. C. Deshmukh et al, Phys. Rev. A \textbf{89} 053424 (2014); [5] G. Dixit et al, Phys. Rev. Lett. \textbf{111} 203003 (2013); [6] W. R. Johnson and C. D. Lin, Phys. Rev. A \textbf{20} 964 (1979). [Preview Abstract] |
|
Q1.00139: A self-referencing attosecond interferometer Jan Tross, Georgios Kolliopoulos, Carlos A. Trallero-Herrero We demonstrate an experimental tool for the controlled interferometric measurement of two beating trains of attosecond pulses with 13 attoseconds in resolution and hundreds of zeptoseconds in precision. The attosecond pulse train is generated by higher order harmonics from two sources in a gas medium. By controlling the offset phase between the two trains of attosecond pulses we are able to measure the phase difference of the harmonics, emanated from the two distinct sources, relative to the offset phase of the fundamental $f_0$. We find that the phase difference evolution for all the measured harmonics follows the linear relation $\delta \phi_{q} = (2n+1)f_0$, $q$ being the harmonic order. This represents an ideal source for homodyne spectroscopic measurements in the XUV regime. Phase measurements were performed with a resolution of 12.5 attoseconds or half of the atomic unit of time. The precision of the measurement is in the hundreds of zeptoseconds which can be enhanced in further experiments. Finally, no carrier envelope phase stabilization nor generation of isolated attosecond pulses is required for the presented measurements, thus reducing the complexity of future experiments. [Preview Abstract] |
|
Q1.00140: ELECTRON-MOLECULE COLLISIONS |
|
Q1.00141: N($^{\mathrm{2}}$P) Production in electron-N$_{\mathrm{2}}$ Collisions. J William McConkey, Wladek Kedzierski, Jeffery Dech A unique detector which is selectively sensitive to low energy metastable atoms, is used to study the production of ground configuration N($^{\mathrm{2}}$P) atoms following collisions of low energy (0-300 eV) electrons with molecular nitrogen. Time-of-flight detection has allowed identification of at least two dissociation channels with significant differences in released kinetic energy of the fragments. Excitation probability measurements will be presented as a function of incident electron energy and near-threshold data will be used to help identify possible excitation channels. [Preview Abstract] |
|
Q1.00142: HCl$^{\mathrm{+}}$, H$_{\mathrm{2}}$Cl$^{\mathrm{+}}$, DCl$^{\mathrm{+}}$, D$_{\mathrm{2}}$Cl$^{\mathrm{+}}$ dissociative recombination, 300-500 K. Thomas M. Miller, Justin P. Wiens, Nicholas S. Shuman, Albert A. Viggiano We have used a flowing afterglow Langmuir probe apparatus to measure dissociative recombination (DR) rate coefficients at 300-500 K for HCl$^{\mathrm{+}}$, H$_{\mathrm{2}}$Cl$^{\mathrm{+}}$, DCl$^{\mathrm{+}}$, and D$_{\mathrm{2}}$Cl$^{\mathrm{+}}$. For 300 K, we find 7.7 x 10$^{\mathrm{-8}}$ cm$^{\mathrm{3}}$/s (HCl$^{\mathrm{+}})$, 2.6 x 10$^{\mathrm{-7}}$ cm$^{\mathrm{3}}$/s (H$_{\mathrm{2}}$Cl$^{\mathrm{+}})$, and 1.1 x 10$^{\mathrm{-7}}$ cm$^{\mathrm{3}}$/s (D$_{\mathrm{2}}$Cl$^{\mathrm{+}})$, each with about 35{\%} accuracy. The DR rate coefficient for DCl$^{\mathrm{+}}$ is too slow for us to measure, especially in the face of dealing with mixed H/D species formed in apparatus feedlines when introducing DCl. DR rate coefficients are needed in modeling chlorinated species in diffuse interstellar molecular clouds,$^{\mathrm{1}}$ though at much lower temperatures than we can reach. Cl$^{\mathrm{+}}$ exists in diffuse clouds because IE(Cl) \textless IE(H), so Cl is not shielded from starlight UV by the abundant H. Cl$^{\mathrm{+}}$ is exothermic to form HCl$^{\mathrm{+}}$ in collision with H$_{\mathrm{2}}$, and a second collision is exothermic to yield H$_{\mathrm{2}}$Cl$^{\mathrm{+}}$. Storage ring experiments$^{\mathrm{2}}$ should yield product branching for the DR reactions. The reaction cycle is repeated from Cl neutrals produced in the DR process. 1. D. A. Neufeld and M. G. Wolfire, Astrophys. J. \textbf{706}, 1594 (2009). 2. O. Novotn\'{y}, et al., Astrophys. J. \textbf{777}, 54 (2013). [Preview Abstract] |
|
Q1.00143: Long-lived metastable anions in fullerene molecules. Alfred Msezane, Zineb Felfli The Regge pole method is benchmarked on the measured electron affinities of C$_{\mathrm{60}}$, C$_{\mathrm{70}}$, C$_{\mathrm{76}}$, C$_{\mathrm{82}}$ and C$_{\mathrm{92}}$ through the calculated electron elastic scattering total cross sections in the electron energy range 0.02 $\le $ E $\le $ 10.0 eV. The method is then used to explore core-polarization induced long-lived metastable negative ions formation as resonances in these fullerenes. Indeed, the calculated total elastic cross sections for these fullerenes have been found to behave very much like those of their ground states. They are characterized generally by Ramsauer-Townsend (R-T) minima, shape resonances and dramatically sharp resonances manifesting long-lived metastable negative ion formation at 1.86 eV, 1.77 eV, 2.20 eV, 1.72 eV and 2.35 eV for C$_{\mathrm{60}}$\textasciimacron , C$_{\mathrm{70}}$\textasciimacron , C$_{\mathrm{76}}$\textasciimacron , C$_{\mathrm{82}}$\textasciimacron and C$_{\mathrm{92}}$\textasciimacron , respectively. These core polarization-induced long-lived metastable cross sections, with their second R-T minima and resonance positions close to those of their respective ground states, demonstrate the importance of identifying and delineating the resonance structures in low-energy electron scattering from fullerenes in general. [Preview Abstract] |
|
Q1.00144: Simple method for determining binding energies of fullerene and complex atomic negative ions. Zineb Felfli, Alfred Msezane A robust potential which embeds fully the vital core polarization interaction has been used in the Regge pole method to explore low-energy electron scattering from C$_{\mathrm{60}}$, Eu and Nb through the total cross sections (TCSs) calculations. From the characteristic dramatically sharp resonances in the TCSs manifesting negative ion formation in these systems, we extracted the binding energies for the C$_{\mathrm{60}}$\textasciimacron , Eu\textasciimacron and Nb\textasciimacron anions; they are found to be in outstanding agreement with the measured electron affinities of C$_{\mathrm{60}}$[1], Eu[2, 3] and Nb[4]. Common among these considered systems, including the standard atomic Au is the formation of their ground state negative ions at the second Ramsauer-Townsend (R-T) minima of their TCSs. Indeed, this is a signature of all the fullerenes and complex atoms considered thus far. Shape resonances, R-T minima and binding energies of the resultant anions are presented. [1] D. --L. Huang\textit{ et al. }J. Chem. Phys. \textbf{140,} 224315 (2014) [2] S. -B. Cheng and A.W. Castleman, Jr., Sci. Rep. \textbf{5}, 12414 (2015) [3] V. T. Davis and J. S. Thompson, J. Phys. B \textbf{37}, 1961 (2004) [4] Z. Luo \textit{et al}. Phys. Rev. A \textbf{93}, 020501(R) (2016) [Preview Abstract] |
|
Q1.00145: Resonances in low-energy electron elastic scattering from Fullerenes C$_{\mathrm{60}}$ through C$_{\mathrm{92}}$ Zineb Felfli, Alfred Msezane The electron affinity (EA) provides a stringent test of theory when the calculated and measured EAs are compared. A strong motivation for the fundamental investigations of low-energy electron elastic scattering from the selected fullerenes C$_{\mathrm{60}}$, C$_{\mathrm{70}}$, C$_{\mathrm{74}}$, C$_{\mathrm{80}}$, C$_{\mathrm{82}}$, C$_{\mathrm{84}}$ and C$_{\mathrm{92}}$ is the availability of high quality measured EAs [1, 2]. The Regge pole calculated electron elastic total cross sections for these fullerenes are found to be characterized generally by Ramsauer--Townsend (R-T) minima, shape resonances and dramatically sharp resonances manifesting stable negative ion formation. The extracted binding energies for the resultant anions agree excellently with the measured EAs of the fullerenes listed above, giving great credence to the Regge pole method and confirming that fullerenes behave like ``big atoms'' [3]. Common among all these fullerenes is the appearance of their ground state negative ions at their second R-T minima, similarly to the atomic Au case. 1. D.-L. Huang \textit{et al}, J. Chem. Phys. \textbf{140}, 224315 (2014) 2. O. V. Boltalina \textit{et al}, Rapid Commun. Mass Spectrom. \textbf{7}, 1009 (1993) 3. M. Ya Amusia, Chem. Phys. \textbf{414}, 168 (2013) [Preview Abstract] |
|
Q1.00146: Rydberg scattering in $\mbox{K(12p)-CH}_{\mbox{3}} \mbox{NO}_{\mbox{2}} $ collisions: role of transient ion pair states M. Kelley, S. Buathong, F. B. Dunning Studies of heavy-Rydberg ion pair formation through non-dissociative electron transfer in collisions between Rydberg atoms and attaching targets have focused on targets that form valence-bound anions. Collisions with $\mbox{CH}_{\mbox{3}} \mbox{NO}_{\mbox{2}} $, lead to formation of dipole-bound anions which can, through internal couplings, result in creation of valence-bound anions. Our measurements, however, provide no evidence for formation of long-lived ion pair states. Rather, the data show that collisions lead to strong Rydberg atom scattering with collision cross sections comparable to the geometrical size of the Rydberg atom. This scattering is attributed to creation of transient $\mbox{K}^{\mbox{+}}\mbox{..CH}_{\mbox{3}} \mbox{NO}_{\mbox{2}}^{\mbox{-}} $ ion-pair states with lifetimes sufficient to allow significant scattering of the $\mbox{K}^{+}$and $\mbox{CH}_{\mbox{3}} \mbox{NO}_{\mbox{2}}^{\mbox{-}} $ ions but which, on time scales $\mathop >\limits_{\sim } $ 10 ps, are destroyed by field-induced detachment from the anion due to the field of the $\mbox{K}^{+}$ion. Following detachment, the electron remains bound to the $\mbox{K}^{+}$ion in a Rydberg state. [Preview Abstract] |
|
Q1.00147: Dissociative recombination of HCN+ and HNC+, a simplified approach Erin McBroom, Nicolas Douguet, Samantha Fonseca, Asa Larson, Ann Orel We present the study of the Dissociative Recombination (DR) of the HCN$^+$ and HNC$^+$ molecular ions. Our calculations are based on a simplified theoretical model that captures the essence of indirectly driven DR process. We use normal modes to represent the vibrational states and the non-adiabatic couplings between them are obtained simply by computing the scattering matrix elements in this vibrational space. Electronic structure calculations, as well as scattering calculations, were carried out entirely from ab initio principles and we compare our results to available data on the literature. [Preview Abstract] |
|
Q1.00148: Dissociative Excitation of Adenine by Electron Impact. J William McConkey, Joshuah Trocchi, Jeffery Dech, Wladek Kedzierski Dissociative excitation of adenine (C$_{\mathrm{6}}$H$_{\mathrm{5}}$NH$_{\mathrm{2}})$ into excited atomic fragments has been studied in the electron impact energy range from threshold to 300 eV. A crossed beam system coupled to a vacuum ultraviolet (VUV) monochromator is used to study emissions in the wavelength range from 110 to 200 nm. The beam of adenine vapor from a stainless steel oven is crossed at right angles by the electron beam and the resultant UV radiation is detected in a mutually orthogonal direction. The strongest feature in the spectrum is H Lyman-$\alpha $. [Preview Abstract] |
|
Q1.00149: Momentum imaging of the dissociation dynamics for dissociative electron attachment to CF$_4$ and dipolar dissociation of O$_2$ D. Reedy, A. Nemer, R. Strom, A. Edmonds, T.J. Gay, E. Miliordos, A.L. Landers, M. Fogle We present experimental results for dissociative electron attachment (DEA) to CF$_4$ and diploar dissociation of O$_2$. From our ion-momentum imaging results we extract anion fragment kinetic energies and angular distributions with respect to the incoming electron beam. From these we can directly observe the dissociation dynamics associated to the formation of transitory negative ions. For the DEA to CF$_4$, we have measured both dissociation pathways which lead to CF$_3^-$ and F$^-$ anions. For the CF$_3^-$ pathway, we have investigated the kinetic energy release (KER) as a function of incident electron energy and find a result that is contrary to previous experimental observations. For the F$^-$ dissociation channel, we observe both high and low KER channels. We have made detailed investigations of these channels in terms of angular distributions, which suggest the state symmetries involved. For the dipolar dissociation of O$_2$, we investigate the formation of positive and negative ion pair production due to electron-impact excitation. We will compare theoretical calculations with the momentum imaging results. [Preview Abstract] |
|
Q1.00150: ATOMIC AND MOLUCULAR STRUCTURE AND PROPERTIES |
|
Q1.00151: Van der Waals pentamers. Jianing Han We report on the five-body repulsive van der Waals interactions in the strongly dipole-dipole coupled Rydberg states. Compared to three-body and four-body interactions, five-body van der Waals interactions show more energy levels and more potential wells caused by avoided crossings. This research bridges the few-body physics and many-body physics. Other disciplines, such as chemistry, biology, and medical field, will also benefit from better understanding van der Waals interactions. [Preview Abstract] |
|
Q1.00152: Closed-channel fraction of a strongly interacting Fermi Gas. Xiang-Pei Liu, Hao-Ze Chen, Xing-Can Yao, Xiao-Qiong Wang, Yu-Xuan Wang, Yu-Ping Wu, Qi-Jin Chen, Yu-Ao Chen, Jian-Wei Pan Near a Feshbach resonance, the many-body state of paired atoms is the so-called dressed molecule which can be understood as a linear combination of open-channel atom pairs and closed-channel bare molecules. The closed-channel fraction plays a crucial role in the description of the BEC-BCS crossover since it quantifies the mixing between the atom pairs and the bare molecules. In this presentation, I will first show the experimental procedure for producing of large degenerate Fermi gas. With advanced laser cooling and sympathetic cooling, we are able to obtain a maximum molecule number of 3×10$^{\mathrm{6}}$ at T/T$_{\mathrm{F}}$\textasciitilde 0.06. The low temperature and large atom number allow us to study the closed-channel fraction over a wide parametric range (scattering length, fermi momentum and temperature). With a molecule probe laser, we are able to extract the closed-channel fraction in the BEC-BCS crossover. Experimental results show a good agreement with the prediction of two-channel model. [Preview Abstract] |
|
Q1.00153: Calculations of long-range three-body interactions for Li($2S$)-Li($2S$)-Li$^{+}$($1S$) Pei-Gen Yan, Li-Yan Tang, Zong-Chao Yan, James F Babb We theoretically investigate long-range interactions between a ground state Li$^+$ ion and two ground state neutral Li atoms with highly accurate variationally-generated wave functions in Hylleraas coordinates. Using perturbation theory for the energies up to third-order, we evaluate the coefficients $C_4$, $C_6$ and $C_8$ of the second order dispersion interactions and the coefficients $C_7$ and $C_9$ of the third-order additive and nonadditive interactions. The nonadditive interactions coefficients depend on the geometrical configurations of this three-body system and on the different positions of the ion for each configuration. Our calculations may be of interest for the study of three-body recombination and for constructing potential energy surfaces. [Preview Abstract] |
|
Q1.00154: ABSTRACT WITHDRAWN |
|
Q1.00155: Breaking Into the Nuclear and Nucleosynthesis Codes Eugene Pamfiloff In 1964, astrophysicists John N. Bahcall showed that there was no evidence in support of the stellar model regarding the fusion of plasma protons into helium nuclei and provided a plan to measure the neutrino emission from the sun for that proof of concept. For every four protons that would fuse into helium, two e-neutrinos should be emitted. But sadly the tests failed, as only 25{\%} of the predicted flux was discerned. Subsequent attempts to modify the stellar and particle models to account for the missing neutrinos left inconclusive results. To find that supportive evidence, a study of the reverse of fusion comprising 2753 unstable isotopes was undertaken. This provided an archive of new information. That data disclosed both confirmations of many contemporary theories and assumptions for which no factual basis existed, as well as contradictions of several models and other universally accepted conclusions. These confirmations and contradictions are expressed in three formats under the above title. They include a power-point presentation, a paper that briefly describes some notable results, and the sum of the findings are detailed in a recent book. One of the primary topics of this work is in reference to the methods by which positively charged particles assemble into multi-particle nuclei, specifically those containing the highest quantity of nucleons. Although it is subject to peer review, nevertheless several persistent problems in stellar and nuclear physics have been unraveled by this research. For additional information, contact the author. [Preview Abstract] |
|
Q1.00156: Piezoelectricity Enhancement and Band Structure Modification of Single Atomic Shift in MoS$_{\mathrm{2}}$ Supercell Monolayer Felix Jaetae Seo, Sheng Yu, Quinton Rice, Shopan Hafiz, Bagher Tabibi, Qiliang Li A monolayer of transition metal dichalcolgenides (TMDCs, TM: Mo, W, DC: S, Se, Te) has second-order nonlinearity including piezoelectricity responding to an external field due to spatial inversion asymmetry. The intrinsic piezoelectric coefficient (e$_{\mathrm{11}})$ of MoS$_{\mathrm{2}}$ without any atomic shift has \textasciitilde 298 pC/m, where e$_{\mathrm{11}}$ indicates the sum of ionic and electronic polarizations along the armchair direction responding to the uniaxial atomic shift along the armchair direction. The piezoelectric coefficients (e$_{\mathrm{11}})$ of MoS$_{\mathrm{2}}$ supercell with a single atomic shift of Mo- and S-ion positively (20{\%}) along the armchair direction were increased to \textasciitilde 350 pC/m and \textasciitilde 305 pC/m, respectively. Meanwhile, the piezoelectric coefficients (e$_{\mathrm{11}})$ of MoS$_{\mathrm{2}}$ supercell with a single atomic shift of Mo- and S-ion positively (20{\%}) along the zigzag direction have \textasciitilde 330 pC/m. The bandgap energy at the K point in the first Brillion zone of a single atomic shift either Mo- and S-ions positively (20{\%}) along the armchair direction in the MoS$_{\mathrm{2}}$ atomic cell is largely reduced to \textasciitilde 0.06 eV compared to the intrinsic bandgap (1.96 eV) of MoS$_{\mathrm{2}}$ without atomic stain. The large piezoelectricity enhancement and bandgap modification due to a single atomic shift in TMDCs may open astonishing scientific research and applications including quantum information processing and optomechanics in the pico-scale atomic layer. [Preview Abstract] |
|
Q1.00157: Paschen-Back effects and Rydberg-state diamagnetism in vapor-cell electromagnetically induced transparency Lu Ma, David Anderson, Georg Raithel We report on a rubidium vapor-cell Rydberg electromagnetically induced transparency (EIT) experiment in a 0.7~T magnetic field where all involved levels are in the hyperfine Paschen-Back regime, and the Rydberg state exhibits a strong diamagnetic interaction with the magnetic field. Signals from both $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ are present in the EIT spectra. This feature of isotope-mixed Rb cells allows us to measure the strength of strong magnetic fields to within a $0.2$\% relative uncertainty. The measured spectra are in excellent agreement with the results of a Monte Carlo calculation. Line shifts and broadenings due to small inhomogeneities of the magnetic field are included in the model. The method can be extended to even higher fields. [Preview Abstract] |
|
Q1.00158: Harmonic Vibrational Frequencies: Approximate Global Scaling Factors for TPSS, M06, and M11 functional families using several common basis sets. D. O. Kashinski, R. G. Nelson, G. M. Chase, O. E. Di Nallo, E. F. C. Byrd We propose new approximate global multiplicative scaling factors for the DFT calculation of harmonic vibrational frequencies using functionals from the TPSS, M06, and M11 functional families with standard Correlation Consistent cc-pV$x$Z and aug-cc-pV$x$Z ($x=$ D, T and Q), 6-311G split valence family, as well as Sadlej, and Sapporo polarized triple-$\zeta$ basis sets. A total of 99 harmonic frequencies are being calculated for 26 gas phase organic and non-organic molecules typically found in detonated solid propellant residue. The approximate multiplicative scaling factors and associated uncertainties are being determined using a least squares approach comparing the computed harmonic frequencies to experimental counterparts well established in the scientific literature. A comparison of our work to previously published global scaling factors will be made to verify method reliability and the applicability of our molecular test set. An update on the progress of this work will be given at the meeting. [Preview Abstract] |
|
Q1.00159: Enhancement of Rb 5P fine-structure collisional transfer rates in dense inert buffer gas mixtures Alina Gearba, Jeremiah Wells, Randy Knize, Jerry Sell Measurements of collisional fine-structure mixing rates between Rb 5P states in Rb-He-Ar and Rb-He-Xe gas mixtures will be presented. We have found that the Rb-He mixing rates are significantly increased by the addition of Ar or Xe, even though the Rb-Ar or Rb-Xe mixing cross sections are orders of magnitude smaller than that of Rb-He. Using Rb-inert gas interatomic potentials we have developed a model to explain our experimental results. Our model takes into account the decrease in Rb 5P fine-structure splitting at small internuclear distances which occurs at high buffer gas pressures. This results in an effective increase in the collisional excitation transfer cross section with buffer gas pressure. We will compare our experimental results to these simulated results and model what this effect would be in K and Cs with inert buffer gas mixtures. [Preview Abstract] |
|
Q1.00160: Single photoionization cross section measurements of Au$^{\mathrm{+}}$ ions and first determinations of excited state levels in Au$^{\mathrm{2+}}$ David Macaluso, Alfred Mueller, Stefan Schippers, A.L. David Kilcoyne Single photoionization cross-section measurements of Au$^{\mathrm{+}}$ ions were performed using synchrotron radiation and the photo-ion, merged-beams technique at the Advanced Light Source at Lawrence Berkeley National Laboratory. Measurements were made at a photon energy resolution of 18 meV from 18.06 to 25.57 eV spanning the $^{\mathrm{1}}$S$_{\mathrm{0}}$ ground state and $^{\mathrm{3}}$D$_{\mathrm{3}}$ metastable state ionization thresholds. Multiple autoionizing resonance series are identified using quantum defect theory. These series identifications were used to make preliminary determinations of low-lying excited state energy levels in the product Au$^{\mathrm{2+}}$ ion, representing the first experimental determination of these levels. [Preview Abstract] |
|
Q1.00161: LMn and LNn (n $\geq$ 4) dielectronic resonances in the M-shell ions of tungsten N/A Dipti, Alexander Borovik, Jr., Roshani Silwal, Joan M. Dreiling, Endre Takacs, Yuri Ralchenko The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was used to produce x-ray spectra ($E_{ph}$ = 7 keV to 16 keV) from highly-charged ions of tungsten with the beam energy varying between 7 keV and 11 keV. The spectra recorded with the high-purity Ge solid-state detector are primarily due to stabilizing radiative decays of autoionizing states produced during dielectronic capture of the beam electrons by tungsten ions. The identifications of the spectral features are based on a very good agreement with the large-scale collisional-radiative (CR) simulations of the EBIT plasma performed with the non-Maxwellian code NOMAD. The Flexible Atomic Code, in both relativistic configuration and fine-structure modes, was used to generate extensive atomic data for CR modeling. It was found that the measured spectra contain contributions from a large number of inner-shell dielectronic resonances LMn and LNn (n $\geq$ 4) in Mn-like W$^{49+}$ through Ne-like W$^{64+}$ ions. The interpretation of measurements as well as the details of theoretical simulations will be presented. [Preview Abstract] |
|
Q1.00162: The spectrum of doubly ionized silver: Ag III Ankita Saxena, Tauheed Ahmad Doubly ionized silver, isoelectronic with Rh I has ground configuration 4p$^6$4d$^9$ and the excited configurations are of the type 4d$^8$nl (n$>$3) and 4p$^5$4d$^{10}$. The spectrum of Ag III has been studied in the wavelength region 350-2074 {\AA}. The spectra needed for the analysis were recorded on 3-m normal incidence vacuum spectrograph at Antigonish Laboratory, Canada. The analysis of this spectrum was started by Gibbs and White establishing the ground doublet followed by Gilbert, Shadmi and lastly by Benschop et al. At present only two excited configurations 4d$^8$5p and 4d$^8$5s have been studied apart from the ground doublets. In the present work we have undertaken the study of two major configurations 4d$^8$(5d+6s) which comprising of 83 energy levels,with the aid of Relativistic Hartree-Fock (HFR) method and least square fitted parametric calculations using Cowan Code. All the previously reported values for 4d$^8$5p and 4d$^8$5s have been confirmed except the two levels of 4d$^8$5p configuration. J value of one of the level at 135626.7 cm-1 has been changed from J=0.5 to J=1.5 and new level for J=0.5 is established at 135778.4 cm-1. The work is still in progress and the new findings will be presented. [Preview Abstract] |
|
Q1.00163: Bound and Quasibound States of the Negative Ion of Lanthanum (La$^{-}$) Studied by Photodetachment Spectrsocopy C.W. Walter, N.D. Gibson, N.B. Lyman, J. Wang The negative ion of lanthanum, La$^{-}$, has the richest bound state spectrum ever observed for an atomic negative ion [1], and it has been proposed as perhaps the best candidate for laser cooling of a negative ion [2,3]. In the present experiments, La$^{-}$ is investigated using tunable infrared spectroscopy. The relative signal for neutral atom production was measured with a crossed ion-beam--laser-beam apparatus over the photon energy range 520-900 meV to probe the continuum region above the La neutral atom ground state. The spectrum shows multiple resonance peaks due to transitions to quasibound excited states of La$^{-}$ which subsequently autodetach. In addition, photodetachment thresholds are observed to excited states of La. The measured spectrum is consistent with the recently reported revised electron affinity for lanthanum [4]. \\[4pt] [1] C.W. Walter, N. D. Gibson, D. J. Matyas, C. Crocker, K. A. Dungan, B. R. Matola, J. Rohlen, \textit{Phys. Rev. Lett.} \textbf{113}, 063001 (2014); [2] S.M. O’Malley and D.R. Beck, \textit{Phys. Rev. A} \textbf{81}, 032503 (2010); [3] E. Jordan, G. Cerchiari, S. Fritzsche, A. Kellerbauer, \textit{Phys. Rev. Lett.} \textbf{115}, 113001 (2015); [4] L. Pan and D.R. Beck, \textit{Phys. Rev. A} \textbf{93}, 062501 (2016). [Preview Abstract] |
|
Q1.00164: Using coherent molecular motion to merge electron diffraction with x-ray spectroscopic results Kareem Hegazy, Markus Illchen, Jie Yang, Xiaozhe Shen, Renkai Li, Theodore Vecchione, Jeff Corbett, Alan Fry, Nick Hartmann, Carsten Hast, Keith Jobe, Igor Makasyuk, Joseph Robinson, Sharon Vetter, Stephen Weathersby, Charles Yoneda, Xijie Wang, Ryan Coffee Ultrafast electron diffraction (UED) has recently been shown to probe ultrafast time dependent molecular structure. If such structural measurements could be connected to spectroscopic measurements, one could better understand the interaction between the electronic and the nuclear degrees of freedom. As a first step, we diffract MeV scale electrons, time-resolved, following repeated impulsive stimulated Raman excitation of an ensemble wide coherent rotational revival in N2O. An identical molecular alignment procedure was used in a previous soft x-ray spectroscopic experiment at the Linac Coherent Light Source (LCLS). Both experiments clearly reveal the molecular alignment signature which can be used to merge the data sets. [Preview Abstract] |
|
Q1.00165: Laser cooling of BaF. Yan Bo, Wenhao Bu, Tao Chen, Guitao Lv In this poster, we report our recently experimental progresses in laser cooling of BaF molecule. Our theoretic calculation shows BaF is a good candidate for laser cooling: quasi-cycling transitions, good wavelengths (around 900nm) for the main transitions. We have built a 4K cryogenic machine, laser ablate the target to make BaF molecules. The precise spectroscopy of BaF is measured and the laser cooling related transitions are identified. The collision between BaF and 4K He is carefully characterized. The quasi-cycling transition is demonstrated. And laser cooling experiment is going on. [Preview Abstract] |
|
Q1.00166: Fermion superuid with hybridized s- and p-wave pairings Lihong Zhou, Wei Yi, Xiaoling Cui Ever since the pioneering work of Bardeen, Cooper and Schrieffer in the 1950s, exploring novel pairing mechanisms for fermion superfluids has become one of the central tasks in modern physics. Here, we investigate a new type of fermion superfluid with hybridized s- and p-wave pairings in an ultracold spin-1/2 Fermi gas. Its occurrence is facilitated by the co-existence of comparable s- and p-wave interactions, which is realizable in a two-component 40K Fermi gas with close-by s- and p-wave Feshbach resonances. The hybridized superfluid state is stable over a considerable parameter region on the phase diagram, and can lead to intriguing patterns of spin densities and pairing elds in momentum space. In particular, it can induce a phase-locked p-wave pairing in the fermion species that has no p-wave interactions. The hybridized nature of this novel superfluid can also be confirmed by measuring the s-wave and p-wave contacts, which can be extracted from the high- momentum tail of the momentum distribution of each spin component. These results enrich our knowledge of pairing superfluidity in Fermi systems, and open the avenue for achieving novel fermion superfluids with multiple partial-wave scatterings in cold atomic gases. [Preview Abstract] |
(Author Not Attending)
|
Q1.00167: Nonequilibrium Hall Response After a Topological Quench F. Nur Unal, Erich Mueller, M. O. Oktel We theoretically study the Hall response of a lattice system following a quench where the topology of a filled band is suddenly changed. In the limit where the physics is dominated by a single Dirac cone, we find that the change in the Hall conductivity is two-thirds of the quantum of conductivity. We explore this universal behavior in the Haldane model, and discuss cold-atom experiments for its observation. Beyond linear response, the Hall effect crosses over from fractional to integer values. We investigate finite-size effects, and the role of the harmonic confinement. Furthermore, we explore the magnetic field quenches in ladders formed in synthetic dimensions. [Preview Abstract] |
|
Q1.00168: Characterizations of SiN and AlN microfabricated waveguides for evanescent-field atom-trap applications Jongmin Lee, Matt Eichenfield, Erica Douglas, John Mudrick, Grant Biedermann, Yuan-Yu Jau Trapping neutral atoms in the evanescent fields generated by microfabricated nano-waveguides will provide a new platform for neutral atom quantum controls via strong atom-photon interactions. At Sandia National Labs, we are aiming at developing the related technology that can enable the efficient optical coupling to the waveguide at multiple wavelengths, fabrication nano-waveguides to handle required optical power, more robust waveguide structure, and the new fabrication geometry to facilitate the cold-atom experiments. We will report our latest results on the related subjects. [Preview Abstract] |
|
Q1.00169: ABSTRACT WITHDRAWN |
|
Q1.00170: ABSTRACT WITHDRAWN |
|
Q1.00171: High temperature superconducting surface ion traps. Kirill Lakhmanskiy, Philip Holz, Dominic Schärtl, Muir Kumph, Yves Colombe, Rainer Blatt Traps are known to be a good tool to perform quantum simulations [1] and quantum computation [2]. Large scale quantum systems can be achieved by surface ion traps. However, the closeness of the ions to the trap's surface leads to an increase of the heating rate of the motional state, which degrades the fidelity of quantum operations. The origin of this heating is not well understood [3]. understand different sources of motional heating, we use a surface ion trap made of YBCO, a high-temperature superconducting material. We designed our trap in such a way that Johnson noise is the dominant source of motional heating above the critical temperature Tc, whereas below Tc it should be negligible compared to other noise sources. By measuring the motional heating rate of a trapped ion, we observe large changes in the magnitude of the electric field noise in a small temperature range around Tc, which is consistent with our calculations. demonstrates an effect of the Johnson noise on the heating rate of the ion. [1] R. Blatt and C.F. Roos, Nature Phys. 8, 277 (2012) [2] . Blatt and D. Wineland, Nature 453, 1008 (2008) [3] M. Brownnutt, M. Kumph, P. Rabl, and R. Blatt, Rev. Mod. Phys. 87, 1419 (2015) [Preview Abstract] |
|
Q1.00172: It may be possible to use Microscopic Black Holes as a Propulsion Beam Richard Kriske Several years ago during the commissioning of the LHC, the question as to whether a miniature Black Hole would be formed, and what to do with it if it was, came up as a legitimate topic of discussion. It was calculated at that time that although it was possible, the possibility was extremely small, and it would evaporate quickly, and would be safely ejected into space, as its mass would be so great as to simply continue along its inertial path, out the end of the circular LHC accelerator. New improvements to the LHC are the increase in energy to about 15 TEV. Linear accelerators, such as the ILC, claim to be able to produce much higher TEV, as they collide electrons and positrons, as opposed to Protons, as does the LHC. This author has heard incredible numbers, such as 250 TEV, with a beam current of 1 Amp. With this incredible increase in Energy and Current, one could turn the Black Hole investigation around, and try to determine how one could produce a steady stream of Microscopic Black Holes. A Black Hole machine. When the Black Holes evaporate do they expand, space in space time. Would the old theory of expanding space behind a craft warp space, and enable the craft to exceed the speed of light. The warp theory was proposed before Star Trek, is it now feasible to prove? [Preview Abstract] |
|
Q1.00173: Near-threshold photodetachment spectroscopy and THz spectroscopy of NH$^{-}_{2}$ Olga Lakhmanskaya, Malcolm Simpson, Simon Murauer, Eric Endres, Viatcheslav Kokoouline, Roland Wester NH$^{-}_{2}$ ions are known to be interesting species for understanding interstellar nitrogen chemistry [1]. Recent astronomical observations showed that an unidentified absorption feature at 933.973-934.009 GHz might be associated to p-NH$^{-}_{2}$ [1]. We, therefore, present findings on near-threshold photodetachment spectroscopy of the amide anion NH$^{-}_{2}$ performed in a cold (10 K) 22-pole ion trap. The spectrum reveals step features which are associated with specific transitions between rotational levels of the ground vibrational state of NH$^{-}_{2}$ (X$^1$A$_1$ electronic state) and NH$_2$ (X$^2$B$_1$ electronic state). With this data we can significantly improve the determination of the electron affinity of amidogen NH$_2$ and access the fundamental rotational transition of p-NH$^{-}_{2}$. [1] C. M. Persson, M. Hajigholi, G. E. Hassel, A. O. H. Olofsson, J. H. Black, E. Herbst, H. S. P. M\"{u}ller, J. Cernicharo, Wirstr\"{o}m, M. Olberg, \AA. Hjalmarson, D. C. Lis, H. M. Cuppen, M. Gerin, and K. M. Menten 2014 \emph{Astronomy \& Astrophysics} [Preview Abstract] |
|
Q1.00174: A telecom-wavelength conversion from near-infrared light based on a cold Rubidium atomic ensemble Wei Chang, Yunfei Pu, Nan Jiang, Chang Li, Sheng Zhang, Luming Duan Exponential photon transmission losses in fiber is a severe limitation to realize long-distance quantum communication. It's helpful to use telecom-wavelength photon transmission to mitigate these absorption losses. However, typical atomic electronic transition from ground-level is in visible wavelengths or near-infrared wavelengths, such as transitions based on Rubidium. Here we report our progress in telecom-wavelength conversion from 780nm to 1475nm and from 795nm to 1530nm in a cold optically thick gas of Rubidium. Both these two conversions are using a diamond configuration transition that we use 5S$_{\mathrm{1/2}}$-5P$_{\mathrm{3/2}}$-4D$_{\mathrm{3/2}}$ cascade transition for the 780nm to 1475nm route and 5S$_{\mathrm{1/2}}$-5P$_{\mathrm{1/2}}$-4D$_{\mathrm{3/2}}$ cascade transition for the 795nm to 1530nm route. [Preview Abstract] |
|
Q1.00175: Highly polarized 1D Fermi gases near p-wave resonance Yinfeng Ma, Xiaoling Cui Based on the recently developed interaction renormalization for 1D p-wave interaction, we study the polaron physics in the 1D spin-1/2 Fermi gas near p-wave resonance. We use the variational approach up to two particle-hole excitations on top of the unperturbed Fermi sea, and find good convergence to the attractive polaron energy. We show that the attractive polaron becomes energetically unstable to the molecule formation as increasing the interaction strength, while the repulsive polaron branch features a broadened spectral width as approaching resonance indicating the instability due to atom loss. These properties are distinct from the polaron physics in 1D s-wave interacting Fermi gases, but share essential similarity to the 3D fermion system across s-wave resonance. [Preview Abstract] |
|
Q1.00176: The Road to DLCZ Protocol in Rubidium Ensemble Chang Li, Yunfei Pu, Nan Jiang, Wei Chang, Sheng Zhang Quantum communication is the powerful approach achieving a fully secure information transferal. The DLCZ protocol ensures that photon linearly decays with transferring distance increasing, which improves the success potential and shortens the time to build up an entangled channel. Apart from that, it provides an advanced idea that building up a quantum internet based on different nodes connected to different sites and themselves. In our laboratory, three sets of laser-cooled Rubidium 87 ensemble have been built. Two of them serve as the single photon emitter, which generate the entanglement between ensemble and photon. What's more, crossed AODs are equipped to multiplex and demultiplex optical circuit so that ensemble is divided into 2 hundred of 2D sub-memory cells. And the third ensemble is used as quantum telecommunication, which converts 780nm photon into telecom-wavelength one. And we have been building double-MOT system, which provides more atoms in ensemble and larger optical density. [Preview Abstract] |
|
Q1.00177: Compact atom interferometer using single laser Sheng-wey Chiow, Nan Yu Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. The complexity of required laser system and the size of vacuum chamber driven by optical access requirement limit the applicability of such technology in size, weight, and power (SWaP) challenging environments, such as in space. For instance, a typical physics package of AI includes six viewports for laser cooling and trapping, two for AI beams, and two more for detection and a vacuum pump. Similarly, a typical laser system for an AI includes two lasers for cooling and repumping, and two for Raman transitions as AI beam splitters. In this presentation, we report our efforts in developing a miniaturized atomic accelerometer for planetary exploration. We will describe a physics package configuration having minimum optical access (thus small volume), and a laser and optics system utilizing a single laser for the sensor operation. Preliminary results on acceleration sensitivity will be discussed. We will also illustrate a path for further packaging and integration based on the demonstrated concepts. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. [Preview Abstract] |
|
Q1.00178: Extraction of Bose-Hubbard parameters from a 1D microscopic model Tom Kristensen, Andrea Simoni The Bose-Hubbard model is a powerful tool to understand the many-body physics of cold atoms in lattices. The link between its parameters and the underlying microscopic model is therefore of outstanding importance. The standard Bose-Hubbard model assumes that (i) the excited energy bands are neglected, (ii) tunneling is allowed only between nearest neighbors and (iii) the interaction only acts on-site. However it has been shown in Ref.~[1] from an exact 2-body 1D calculation that the effective interaction of two cold atoms in a lattice strongly depends on the center-of-mass motion, a behavior not predicted by the standard Bose-Hubbard model. We present here an approach to extract effective Bose-Hubbard parameters from a microscopic two-body model that is based on the solution of the Schrödinger equation in a lattice without approximations. As a crucial intermediate we compute the two-body interacting Green function, expressed in terms of regular and irregular solutions. In order to avoid solution linear-dependence problems, we adapt the algorithm of Ref.~[2] to our spectral-element solution approach. [1] H. Terrier \textit{et al.}, Phys. Rev. A {\bf 93}, 032703 (2016) [2] S. J. Singer \textit{et al.}, J. Chem. Phys. {\bf 87}, 4762 (1987) [Preview Abstract] |
|
Q1.00179: Photoassociation spectroscopy of a degenerate Fermi gas of 173 Ytterbium atoms Jeong Ho Han, Jin Hyoun Kang, Moosong Lee, Yong-il Shin We report photoassociation (PA) spectroscopy of ultracold $^{173}$Yb fermions near dissociation limit with dipole-forbidden intercombination transition. The photoassociative spectrum is measured with red-detuned lasers over a scan range up to 1GHz with respect to the F=5/2 $\rightarrow$ F$^\prime$=7/2 atomic resonance. Because of the high nuclear spin (I=5/2) nature of the system, we observe a complicated structure appears with several vibrational series each following the LeRoy-Bernstein progression. We compare our results with a numerical calculation based on a single channel Movre-Pichler model. We also investigate the magnetic field dependence of the photoassociation spectrum. [Preview Abstract] |
|
Q1.00180: Towards a scalable quantum computation platform with solid-state spins in low temperature Wengang Zhang, Xianzhi Huang, Xiaolong Ouyang, Xin Wang, Panyu Hou, Wenqian Lian, Huili Zhang, Chuheng Zhang, Li He, Xiuying Chang, Luming Duan Nitrogen-vacancy (NV) center can be treated as an ``ion" trapped in the diamond lattice. An electron spin triplet ground state (S=1) of NV center can be polarized, coherently manipulated and detected. Together with hyper ne-coupled proximal Carbon-13 and Nitrogen-14 (15) nuclear spins, NV center acts as a promising platform for large scale quantum computation platform at room temperature. By cooling down the diamond to liquid-helium temperature (4K), phonons can be largely suppressed, giving us much longer spin relaxation time (T1) and coherence time (T2) compared with room temperature, and a possibility to readout electron spin state in a single shot. Here we report our progress in building up a prototype for a scalable diamond based quantum computer. [Preview Abstract] |
|
Q1.00181: Experimental realization of an entanglement access network and secure multi-party computation Xiuying Chang, Donglin Deng, Xinxing Yuan, Panyu Hou, Yuanyuan Huang, Luming Duan To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography. [Preview Abstract] |
|
Q1.00182: Fabrication of Diamond for Low Temperature Experiments Wenqian Lian, Li He, Xin Wang, Xinxing Yuan, Huili Zhang, Chuheng Zhang, Xiuying Chang, Panyu Hou, Wengang Zhang, Xiaolong Ouyang, Xianzhi Huang, Luming Duan The nitrogen-vacancy (NV) center in diamond is a promising physical implementation of quantum computing. At low temperature (about 4K), NV center shows a lot of advantages comparing with room temperature. The coherence time of electron spin in NV center is about 10 ms. Besides, the electron spin state read out efficiency is increased by single shot read out scheme. Most importantly, the electron spin can be resonantly driven, so remote NV centers can be entangled by the interference of the resonant zero phonon line photons, which is a promising scheme for the realization of quantum computer based on NV center. Here we show the fabrication work on diamond and the basic test at the low temperature toward quantum network based on NV center. [Preview Abstract] |
|
Q1.00183: Tomography of Correlation Functions in Sodium Bose-Einstein Condensates Haiyu Liang, Tian Tian, Haoxiang Yang, Liyuan Qiu, Anjun Chu, Yanbin Yang, Yingmei Liu, Luming Duan Haiyu Liang 1, Tian Tian 1, Haoxiang Yang 1, Liyuan Qiu 1, Anjun Chu 1, Yanbin Yang 1, Yingmei Liu 2, and Luming Duan 1,3 1. Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, China 2. Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA 3. Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA We present a novel experimental scheme for reconstructing single-particle correlation functions of ultracold atoms from absorption images taken after various time of flights. The efficiency of this scheme is experimentally demonstrated in two different systems, i.e., a sodium Bose-Einstein condensate with an imprinted phase controlled by a digital mirror device, and a quasi-one-dimensional Bose gas of ultracold sodium atoms. This scheme is independent of atomic species, and may thus be applicable to other ultracold atomic systems. [Preview Abstract] |
|
Q1.00184: Fano-Feshbach resonances in ultracold gas of thulium Alexey Akimov, Ivan Cojocaru, Vlad Tsyganok, Emil Davletov, Ilia Luchnokov, Vyacheslav Bushmakin, Elena Kalganova, Vladimir Khlebnikov Fano-Feshbash resonances play important role in controlling interaction between particles in ultracold quantum gasses and quantum simulators. These resonances allow one to change in wide range scattering length of two interacting atoms using magnetic field. While in alkaline atoms these resonances could only be observed in relatively high magnetic fields, in rare earth elements because of high orbital moment in the ground state one could expect number of low-field Fano-Feshbach at low (few Gauss) field. Indeed, such low field resonances been already observed in dysprosium and erbium. In this contribution, we report first observation of low --magnetic field Fano-Feshbach resonances in ultracold thulium. Been on the resonance atoms experience strong modification of the scattering length, which also lead to increased rate of 3-body inelastic collisions and therefore enhanced loss of atoms from the optical dipole trap. In our experiments, atoms were prepared in narrow transition magneto-optical trap and then loaded in optical dipole trap formed by two crossed laser beams at wavelength 532 nm. Then atoms were evaporative cooled and magnetic field depended losses were observed clearly demonstrating number of low field Fano-Fieshbach resonances. [Preview Abstract] |
|
Q1.00185: Vortex cluster shedding in an oblate Bose-Einstein condensate Younghoon Lim, Junhong Goo, Woo Jin Kwon, Joon Hyun Kim, Sang Won Seo, Yong-il Shin We present the observation of vortex cluster shedding from a moving obstacle in an oblate Bose-Einstein condensate (BEC). We investigate the evolution of the vortex shedding pattern as a function of the obstacle velocity v, and observe regular shedding of vortex clusters consisting of two like-sign vortices at low obstacle velocity. As v increases, the vortex shedding pattern becomes irregular with many larger clusters, which shows a transition to turbulence. To quantitatively characterize the vortex shedding pattern, we analyze the cluster charge distribution as a function of the obstacle velocity. The transition from regular to turbulent shedding is manifested with a rapid decrease of fractional population of two like-sign vortex clusters. In particular, we observe a saturating behavior of the Stouhal number with increasing v, which is associated with the shedding frequency. We will discuss possible extension of this work to test the universality of the vortex shedding dynamics. [Preview Abstract] |
|
Q1.00186: Experimental study of vortex dynamics in a highly oblate fermionic condensate~ Bumsuk Ko, Jee Woo Park, Yong-il Shin In a 2D superfluid, quantized vortices are topological point defects whose dynamics reveal the thermodynamic and transport properties of the superfluid. In this presentation, we report on our experimental progress on the study of the vortex dynamics in a fermionic condensate of $^{\mathrm{6}}$Li atoms with strong interactions. We simultaneously trap $^{\mathrm{23}}$Na and $^{\mathrm{6}}$Li atoms in an optically plugged quadrupole trap, and perform forced rf-evaporation of $^{\mathrm{23}}$Na to sympathetically cool $^{\mathrm{6}}$Li. A Fermi gas of about 10$^{\mathrm{6}}$ lithium atoms is prepared in an oblate optical dipole trap (aspect ratio of 1:100) at a temperature of T/T$_{\mathrm{F}}=$0.15. Strong s-wave interactions are induced in a spin-mixture of the two lowest hyperfine states using a broad Feshbach resonance, and a fermionic condensate is formed by evaporative cooling. Using a moving optical obstacle, we can generate a vortex dipole in the condensate. We will discuss the measurements of the critical velocity for vortex shedding as a function of the interaction strength. [Preview Abstract] |
|
Q1.00187: Observation of the Topological Change Associated with the Dynamical Monodromy Daniel Salmon, Matthew Nerem, Seth Aubin, John Delos Classical mechanics is an old theory and new phenomena do not often appear. A recently predicted phenomenon is called ``Dynamical Monodromy.” Monodromy is the study of the behavior of a system as it evolves ``once around a closed circuit”. Systems that do not return to their original state after forming a closed circuit in some space are said to exhibit ``nontrivial monodromy.” One such system is a collection of non-interacting particles moving in a ``champagne bottle” potential. A loop of trajectories of this system exhibits a topological change when each of the particles traverse a monodromy circuit in Energy-Angular Momentum space (any closed path that encloses the singular point at the origin). This system has been realized using a rigid spherical pendulum, with a permanent magnet at its end. Magnetic fields generated by coils are used to create the champagne-bottle potential, as well as drive the pendulum through the monodromy circuit. [Preview Abstract] |
|
Q1.00188: Topological Changes of Wave Functions Associated with Hamiltonian Monodromy Chen Chen, John Delos Almost everything that happens in classical mechanics also shows up in quantum mechanics when we know where to look for it. A recently discovered phenomenon in classical mechanics involves topological changes in the loops that define action and angle variables as a result of a passage around a ``monodromy circuit''. This phenomenon is known by the short name ``Hamiltonian monodromy'' (or, more ponderously, ``nontrivial monodromy of action and angle variables in integrable Hamiltonian systems''). In this paper, we show a corresponding change in quantum wave functions: these wave functions change their topological structure in the same way that the action and angle loops change. [Preview Abstract] |
|
Q1.00189: Interaction Corrections to Chern Numbers Cheng Li, Tin-Lun Ho Chern numbers play a key role in many areas in physics as they describe the topology of a quantum state. Motivated by the recent experiment by Ian Speilman’s group at NIST (arXiv:1610.06228) on the second Chern number $C_2$ of the Yang monopole, we have studied the effect of particle interaction. We show that interaction will stretch the monopole into an extended manifold of singularity, which will cause a gradual change of the second Chern number as the monopole leaves the 4D surface where $C_2$ is calculated. Such gradual change is in fact contained in the data of the NIST experiment. [Preview Abstract] |
|
Q1.00190: Single-Photon Switching and Entanglement of Solid- State Qubits in an Integrated Nanophotonic System Ruffin Evans, Alp Sipahigil, Denis Sukachev, Michael Burek, Johannes Borregaard, Mihir Bhaskar, Christian Nguyen, Jose Pacheco, Edward Bielejec, Marko Loncar, Mikhail Lukin Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate a platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and observe switching at the single-photon level. Raman transitions are used to realize a single-photon source with a tunable frequency and bandwidth in a diamond waveguide. By measuring intensity correlations of indistinguishable Raman photons emitted into a single waveguide, we observe quantum interference resulting from the superradiant emission of two entangled SiV centers. We also discuss current work to extend the coherence time of the SiV spin degree of freedom, engineer deterministic multi-emitter interactions via the cavity mode, and related work with the Germanium-Vacancy center. [Preview Abstract] |
|
Q1.00191: Progress toward the measurement of nuclear-spin-dependent (NSD) parity non-conserving (PNC) transition in Cesium ground-hyperfine states. Jungu Choi, George Toh, Dan Elliott We report our progress on the measurement of weak-force mixing of the ground hyperfine levels in atomic cesium. The effect of this mixing is manifested through weak amplitudes for transitions, which we will observe using an interference between optical and rf transitions. The cesium atomic beam interacts with rf fields confined in an open cavity via Stark-induced and Parity Non-conserving (PNC) transitions, as well as with optical fields via a strong Raman interaction. We have built the rf cavity resonator from copper-clad substrates and highly-reflecting cylindrical mirrors for the cesium ground hyperfine transition at 9.2 GHz. We performed characterization of the cavity mode that shows good field patterns and a reasonable quality factor of the mode for a few percent uncertainty experiment. We have made other preparations, including improving on phase-locked Raman lasers, to observe interference between optical and rf transitions from which the nuclear anapole moment will be derived. We present preliminary measurement results with focus on how to reduce systematic errors and other challenges we are facing. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700