Bulletin of the American Physical Society
45th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 59, Number 8
Monday–Friday, June 2–6, 2014; Madison, Wisconsin
Session D1: Poster Session I (4:00pm - 6:00pm) |
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Room: Exhibit Hall |
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D1.00001: COLD ATOMS, MOLECULES AND PLASMAS |
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D1.00002: High-Resolution Spectroscopy of Trilobite-Like States of $^{85}$Rb$_2$ Ryan Carollo, Edward Eyler, Phillip Gould, William Stwalley We present high-resolution spectra of low-$n$ trilobite-like states in $^{85}$Rb$_2$. Trilobite states are novel long-range molecular states consisting of a ground-state atom embedded in the Rydberg wavefunction of a second atom. We utilize a bound-bound excitation to populate these states from photoassociated ultracold molecules in high-$v$ levels of the lowest triplet state. The excitation is stimulated by a frequency-doubled pulse-amplified CW laser for narrow linewidth. Upon excitation, the trilobite-like states rapidly autoionize and are mass-selectively detected by an ion detector. Previous detection of these states was done by a broader linewidth conventional pulsed laser as reported in Ref. [1]. This work is supported by the NSF and AFOSR.\\[4pt] [1] M. A. Bellos \textit{et al.}, Phys. Rev. Lett. \textbf{111}, 053001 (2013) [Preview Abstract] |
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D1.00003: Cs Trilobite Molecules and Rydberg atom Interactions Donald Booth, Yang Jin, James Shaffer We present results on our Cs ultracold Rydberg atom experiments involving trilobite molecules and Rydberg atom interactions. Trilobite molecules are predicted to have giant, body-fixed permanent dipole moments ($\sim 1 $kD). We present measurements of the Stark shifts of the trilobite states in Cs due to the application of a constant external electric field. We also will present progress on studies of anisotropic interactions between pairs of Rydberg atoms. We will focus on angular-dependent S-matrix calculations of collisions between 89D+89D Rydberg atom pairs in a 100 mV/cm electric field. In this field, the dipole-dipole interaction dominates over the van-der-Waals interaction, creating a large anisotropy in the potential surfaces. [Preview Abstract] |
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D1.00004: Quantification of the effects of Rydberg atoms on ultra-cold neutral plasma evolution Duncan Tate, Ethan Crockett, Ryan Newell We describe recent developments in our ongoing research in which Rydberg atoms are embedded into an ultra-cold neutral plasma (UNP). Atoms in a specific Rydberg state are embedded in the UNP within 10 ns of its creation using a second pulsed laser system. In such an environment, it is predicted that the plasma electrons may be heated or cooled by the Rydberg atoms (see, for example\footnote{T. Pohl {\it et al.}, {\it Eur. Phys. J. D}, {\bf 40}, 45 (2006)}). We identified an experimental signature that correlates with the plasma electron temperature change, namely, the ``crossover'' between heating and cooling, where the UNP lifetime remains the same when Rydbergs are added. More recently, we have been working on quantifying the amount of heating or cooling that can be achieved using a passive technique. Specifically, we measure the time ($t_\delta$) it takes for the UNP to shed a certain fraction of its electrons ($\delta$) as it expands in a small, externally applied, electric field. The work reported in\footnote{K. Twedt and S. Rolston, {\it Phys. Plasmas}, {\bf 17}, 082101 (2010)} shows that the quantity $t^{-1}_\delta$ is a good proxy for the UNP asymptotic expansion velocity, which in turn depends on $T_{e,0}$. [Preview Abstract] |
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D1.00005: Highly collimated source of cold Rb atoms from a 2-D magneto-optical trap Naty Citlali Cabrera Gutierrez |
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D1.00006: Ultracold plasma expansion rate dependence on non-neutrality Craig Witte, Jacob Roberts Ultracold plasmas are formed by photoionizing a collection of laser cooled atoms. Once formed, these plasmas expand. This expansion is driven by both the thermal energy of the plasma electrons, as well as electrostatic energy owing to non-neutrality. Both the parameters can be experimentally controlled with a significant degree of independence. Combining previous work,\footnote{F. Robicheaux and James D. Hanson, Simulation of the Expansion of an Ultracold Neutral Plasma, Phys. Rev. Lett. {\bf 88}055002, (2002).}$^,$\footnote{D Vrinceanu, G S Balaraman, and L A Collins, The King model for electrons in a finite-size ultracold plasma, J. Phys. A: Math. Theor.{\bf 41} 425501 (2008).} we have developed a theoretical model designed to investigate the dependence of ultracold plasma expansion on the degree of non-neutrality of these plasmas in a parameter range relevant to experiments. We find that variations of the plasma neutrality produce non-negligible changes in predicted electron temperature evolution and plasma expansion rate. Such behavior needs to be taken into account for an accurate interpretation of ultracold plasma parameters relevant to experimental measurements. [Preview Abstract] |
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D1.00007: Measurement of Efimov Resonances in Ultracold Li-Cs Mixtures Jacob Johansen, Shih-Kuang Tung, Karina Jimenez-Garcia, Colin Parker, Cheng Chin We report the measurement of a series of three heteronuclear Efimov resonances between Li-6 and Cs-133. The large mass imbalance between these species reduces the geometric scaling factor from 22.7 (homonuclear case) to 4.88, but also increases technical challenges in combining the two species and overlapping the two clouds. We demonstrate a novel trapping scheme, an oscillating time-averaged optical potential (oTOP), which allows us to dynamically change the size and position of our trapping potential to combine both species. Additionally, we demonstrate a novel locking scheme to facilitate high field imaging in Cs. We combine these technical solutions to create ultracold mixtures of Li-6 and Cs-133 for measurement of Efimov resonances and future experiments in few- and many-body physics. [Preview Abstract] |
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D1.00008: A new approach to driving and controlling precision lasers for cold-atom science Ben Luey, Jeremy Shugrue, Mike Anderson Vescent's Integrated Control Electronics (ICE) Platform is a new approach to controlling and driving lasers and other electoral devices in complex atomic and optical experiments. By employing low-noise, high-bandwidth analog electronics with digital control, ICE combines the performance of analog design with the convenience of the digital world. Utilizing a simple USB COM port interface, ICE can easily be controlled via LabView, Python, or an FPGA. High-speed TTL inputs enable precise external timing or triggering. ICE is capable of generating complex timing internally, enabling ICE to drive an entire experiment or it can be directed by an external control program. The system is capable of controlling up to 8 unique ICE slave boards providing flexibility to tailor an assortment of electronics hardware to the needs of a specific experiment. Examples of ICE slave boards are: a current controller and peak-lock laser servo, a four channel temperature controller, a current controller and offset phase lock servo. A single ensemble can drive, stabilize, and frequency lock 3 lasers in addition to powering an optical amplifier, while still leaving 2 remaining slots for further control needs. [Preview Abstract] |
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D1.00009: Isolated Monopoles in a Spinor Bose-Einstein Condensate Michael Ray, Emmi Ruokokoski, Konstantin Turev, Mikko M\"{o}tt\"{o}nen, David Hall Extending our recent observation of Dirac monopoles in the synthetic magnetic field of a Bose-Einstein condensate [1], we report on studies of isolated monopoles related to the so-called 't Hooft-Polyakov [2,3] monopole. We describe in detail the underlying physical theory of isolated monopole defects, the experimental framework within which they are sought, and corresponding numerical simulations. Recent results will be discussed. \\[4pt] [1] M. W. Ray, E. Ruokokoski, S. Kandel, M. Mottonen, and D. S. Hall, Nature 505, 657 (2014). \newline [2] G. 't Hooft, Nuclear Physics B 79, 276 (1974). \newline [3] A.M. Polyakov, JETP Lett. 20, 194 (1974). [Preview Abstract] |
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D1.00010: Creation of spin monopoles in a 87Rb BEC Azure Hansen, Justin T. Schultz, Nicholas P. Bigelow The study of and search for magnetic monopoles is of fundamental interest across many fields. Monopole-like excitations have been achieved experimentally in solid-state spin ice and polariton systems. Monopole spin textures in BECs have been described theoretically [1, 2]. A coherent, two-photon Raman technique allows us to engineer the phase and amplitude of a ${}^{87}$Rb Bose-Einstein condensate and create spin textures of topological interest [3]. A spin monopole has singular local spin and radial vorticity, which we can create using vector vortex laser beams. Optical imprinting permits multiple monopoles to exist in a single BEC, making the technique well-suited to studying monopole-antimonopole dynamics. \\[4pt] [1] J.J. Garcia-Ripoll, J.I. Cirac, J. Anglin, V.M. Berez-Garcia, and P. Zoller. PRA 61, 053609 (2000) \\[0pt] [2] V. Pietil\"{a} and M. M\"{o}tt\"{o}nen. PRL 103, 030401 (2009) \\[0pt] [3] K. C. Wright, L. S. Leslie, A. Hansen, and N. P. Bigelow. PRL 102, 030405 (2009) [Preview Abstract] |
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D1.00011: A Raman Waveplate for Spinor BECs Justin T. Schultz, Azure Hansen, Nicholas P. Bigelow Bose-Einstein condensates allow for the study of cold-atom analogs of other systems, particularly coherent optical systems. One subject not often explored in the context of atom optics is atomic spin as the analog of optical polarization, which can be described via the Stokes parameters. We present a method for measuring the Stokes parameters of a BEC using a two-photon Raman interaction in conjunction with Stern-Gerlach state separation and absorption imaging. The Raman interaction can be described by a Jones matrix for an arbitrary waveplate acting on the atomic ground states. The retardance is set by the pulse area, and the waveplate angle is set by the relative phase of the optical beams. This technique allows access to the relative phase of the ground states and is important for characterizing exotic spin textures (e.g. Full Bloch BECs) and for measuring the Gouy phase in matter waves. [Preview Abstract] |
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D1.00012: Controlling the Phase of Imprinted Spin Textures in Spinor BECs Justin T. Schultz, Azure Hansen, Nicholas P. Bigelow Multi-photon Raman processes are used to make many complex topological spin textures in spinor BECs such as coreless vortices, non-Abelian vortices, skyrmions, and spin monopoles. Understanding this process is important in controllably writing spin textures into the condensate. We derive analytic expressions for the phases of the states for a two-photon Raman interaction and show that for spatially-dependent Rabi frequencies, time-dependent singularities in these phases lead to density modulations termed a ``Raman Fingerprint" for diabatic pulses [1]. When the two-photon detuning is not zero, an additional phase adjusts the locations of the phase singularities, therefore, allowing control over the size of the imprinted features.\\[4pt] [1] L.S. Leslie, {\it et al.} Laser Physics {\bf 19}, 593 (2009). [Preview Abstract] |
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D1.00013: Quantum dynamics of spin waves in ultracold bosonic systems Sebastian Hild, Peter Schauss, Takeshi Fukuhara, Johannes Zeiher, Frauke Seesselberg, Immanuel Bloch, Christian Gross Ultracold quantum gases in optical lattices are promising candidates to simulate spin Hamiltonians, which describe a variety of different phenomena. Single-site resolved imaging of a single spin species allows for the spatially resolved measurement of spin-spin correlations. The atomic Mott insulator corresponds to a spin polarized state with very low entropy. Together with precise local or global spin manipulation, this allows for the study of the dynamics of precisely defined initial spin states. We report on experiments studying the dynamics of bound and free magnons following local spin flips as well as globally imprinted spin spirals, which are highly excited states of the system. The ability to control the tunneling rate in the ultracold atomic gas allows us to study the scaling behavior of the spin spiral lifetime in one and two dimensions. The data is compared with theoretical predictions based on direct diagonalization. [Preview Abstract] |
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D1.00014: Collective Excitations of Bose-Einstein Condensates In Isotropic and Slightly Anisotropic Traps Andrew Barentine, Dan Lobser, Heather Lewandowski, Eric Cornell Boltzmann proved that the monopole mode of a thermal gas in an isotropic, harmonic and 3D trap is undamped. Bose-Einstein Condensates (BECs) are not classical gases and their weakly interacting nature causes damping at finite temperature in a 3D monopole mode. The large parameter space of the TOP (Time-averaged Orbiting Potential) trap allows for precise control of the trap geometry. Exciting a monopole mode in a BEC as well as its canonical thermal cloud in the hydrodynamic regime will allow us to investigate damping effects in isotropic and slightly anisotropic traps. [Preview Abstract] |
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D1.00015: Experiments with BECs in a Painted Potential: Atom SQUID, Matter Wave Bessel Beams, and Matter Wave Circuits Malcolm Boshier, Changhyun Ryu, Paul Blackburn, Alina Blinova, Kevin Henderson The painted potential is a time-averaged optical dipole potential which is able to create arbitrary and dynamic two dimensional potentials for Bose Einstein condensates (BECs). This poster reports three recent experiments using this technique. First, we have realized the dc atom SQUID geometry of a BEC in a toroidal trap with two Josephson junctions. We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. Second, we have used free expansion of a rotating toroidal BEC to create matter wave Bessel beams, which are of interest because perfect Bessel beams (plane waves with amplitude profiles described by Bessel functions) propagate without diffraction. Third, we have realized the basic circuit elements necessary to create complex matter wave circuits. We launch BECs at arbitrary velocity along straight waveguides, propagate them around curved waveguides and stadium-shaped waveguide traps, and split them coherently at y-junctions that can also act as switches. [Preview Abstract] |
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D1.00016: The critical velocity in the BEC-BCS crossover Jonas Siegl, Wolf Weimer, Kai Morgener, Klaus Hueck, Niclas Luick, Henning Moritz Ultracold fermionic gases are an ideal model system for the study of quantum many-body phenomena. Of particular interest is superfluidity due to the open questions surrounding high-temperature superconductors in solids. One hallmark property of superfluid systems is the critical velocity below which obstacles can move through the fluid without friction. The broad Feshbach resonance of fermionic 6Li quantum gases provides the unique possibility to investigate superfluidity over a wide range of interactions. We stir the gas with a red-detuned laser beam as a local density perturbation. Above the critical velocity heating can be observed. We present high-precision measurements of the critical velocity in the BEC-BCS crossover. Our measurements are in excellent agreement with theoretical predictions for the nature of the excitations ranging from Bogoliubov sound waves in the BEC regime to Cooper pair breaking in the BCS regime. Additionally, we can transfer the three-dimensional 6Li gas to a single layer of a blue-detuned one-dimensional optical lattice. This opens the opportunity to study superfluidity in two-dimensional strongly interacting Fermi gases. [Preview Abstract] |
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D1.00017: Basis-set expansion and truncation approach to interacting Bose particles problem Michelle Wynne Sze, Andrew Sykes, John Corson, John Bohn As ultracold gases push into regimes beyond mean-field physics, alternative approaches are required to follow their behavior. To this end, we investigate a basis set expansion and truncation scheme based on perturbation theory to obtain approximate ground state energies as a function of interaction parameter. We explore the ability of this approach to describe interacting Bose particles in 1D and 3D. [Preview Abstract] |
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D1.00018: Experimental modelling of material interfaces with ultracold atoms Theodore A. Corcovilos, Robert W.A. Brooke, Julie Gillis, Anthony C. Ruggiero, Gage D. Tiber, Christopher A. Zaccagnini We present a design for a new experimental apparatus for studying the physics of junctions using ultracold potassium atoms (K-39 and K-40). Junctions will be modeled using holographically projected 2D optical potentials. These potentials can be engineered to contain arbitrary features such as junctions between dissimilar lattices or the intentional insertion of defects. Long-term investigation goals include edge states, scattering at defects, and quantum depletion at junctions. In this poster we show our overall apparatus design and our progress in building experimental subsystems including the vacuum system, extended cavity diode lasers, digital temperature and current control circuits for the lasers, and the saturated absorption spectroscopy system. [Preview Abstract] |
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D1.00019: Exploring the range of motion of atom traps formed in the diffraction pattern behind a pinhole for quantum computing Ian Powell, Taylor Shannon, Sanjay Khatri, Glen Gillen, Katharina Gillen-Christandl To solve the scalability issue of neutral atom quantum computing, we have investigated the diffraction pattern formed behind an array of pinholes as a possible two-dimensional quantum memory system [1]. Exploiting polarization dependence and varying the incident laser angle may facilitate two-qubit gates by bringing pairs of atoms together and apart controllably [2]. We have both experimentally and computationally explored the limits of the incident laser angle for the traps to remain viable for quantum computing. We will present a quantitative comparison of our computations and direct measurements of the diffraction pattern for a large range of incident angles. We will also discuss our progress towards constructing an experimental setup for transferring atoms from our magneto-optical trap (MOT) to the pinhole traps, including projection of our traps into the MOT cloud (proposed in [3]) and an imaging system to characterize the atom traps.\\[4pt] [1] G. D. Gillen, et al., Phys. Rev. A 73, 013409 (2006).\\[0pt] [2] K. Gillen-Christandl and B. D. Copsey, Phys. Rev. A 83, 023408 (2011).\\[0pt] [3] K. Gillen-Christandl and G. D. Gillen, Phys. Rev. A 82, 063420 (2010). [Preview Abstract] |
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D1.00020: Toward Quantum Magnetism Experiments with Li-7 William Lunden, Jesse Amato-Grill, Ivana Dimitrova, Niklas Jepsen, Yichao Yu, David Pritchard, Michael Messer, David Weld, Graciana Puentes, Wolfgang Ketterle We report on the rapid production of large Li-7 Bose-Einstein condensates in a new apparatus designed for optical lattice emulator experiments. Due to the small mass of lithium, we expect that the timescales for tunneling and superexchange in our experiment are 12 times shorter than those in a comparable Rb-87 lattice experiment. We plan to leverage these short timescales in order to study models of quantum magnetism and to explore the influence of synthetic gauge fields on quantum matter. [Preview Abstract] |
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D1.00021: Quantum Dynamics of Dark and Dark-Bright Solitons beyond the Mean-Field Approximation Sven Kr\"onke, Peter Schmelcher Dark solitons are well-known excitations in one-dimensional repulsively interacting Bose-Einstein condensates, which feature a characteristical phase-jump across a density dip and form stability in the course of their dynamics. While these objects are stable within the celebrated Gross-Pitaevskii mean-field theory, the situation changes dramatically in the full many-body description: The condensate being initially in a dark soliton state dynamically depletes and the density notch fills up with depleted atoms. We analyze this process in detail with a particular focus on two-body correlations and the fate of grey solitons (dark solitons with finite density in the notch) and thereby complement the existing results in the literature. Moreover, we extend these studies to mixtures of two repulsively interacting bosonic species with a dark-bright soliton (dark soliton in one component filled with localized atoms of the other component) as the initial state. All these many-body quantum dynamics simulations are carried out with the recently developed multi-layer multi-configuration time-dependent Hartree method for bosons (ML-MCTDHB). [Preview Abstract] |
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D1.00022: Quantum synchronization of ultracold atoms with dipole-dipole interactions in an optical lattice Bihui Zhu, Juan Restrepo, Ana Maria Rey, Murray Holland Ultracold atoms confined in an optical lattice have been utilized as a powerful platform to study versatile many-body physics both experimentally and theoretically. A recent research focus has been the novel phenomena that would emerge with long-range interactions, which become especially important for atomic clocks where ultrahigh precision can amplify these effects. We develop theoretical models treating the two-level atoms as oscillators and study the synchronization of phases among a large ensemble of atoms coupled by dipole-dipole interactions, where the effect of geometry becomes relevant. We investigate the onset of synchronization and the related phase diagram, and further discuss the parameter regime for potential experimental observation using ultracold atoms such as Strontium. By applying different numerical methods, eg., quantum trajectories and truncated Wigner approximations to compare with the mean-field results, we also explore the underlying role of quantum fluctuations. [Preview Abstract] |
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D1.00023: Progress on adiabatic preparation of an anti-ferromagnetic state of bosons in an optical lattice R. Brown, R. Wyllie, S. Koller, D. Norris, E. Goldschmidt, J.V. Porto We present progress towards the adiabatic preparation of an anti-ferromagnetic (AF) state of bosons in an optical lattice [1]. Starting from a unit filled Mott insulator, we apply a staggered effective Zeeman field on every other lattice site. Microwave addressing of the Zeeman-split sub-lattices [2] creates AF order in a staggered optical lattice. We then remove the staggered field over different time scales and monitor the resulting dynamics of the spin and site populations. Our choice of initial spin flip allows us to prepare either the ground or highest energy spin state within the Mott-insulating manifold. We explore the role of holes and edge state imperfections on potential super-exchange driven dynamics. \\[4pt] [1] Phys. Rev. A, \textbf{81}, 61603 (2010)\\[0pt] [2] Phys. Rev. Lett., \textbf{99}, 20402 (2007) [Preview Abstract] |
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D1.00024: Investigation of Kibble-Zurek Quench Dynamics in a Spin-1 Ferromagnetic BEC Martin Anquez, Bryce Robbins, Thai Hoang, Xiaoyun Yang, Benjamin Land, Christopher Hamley, Michael Chapman We study the temporal evolution of spin populations in small spin-1 $^{87}$Rb condensates following a slow quench. A ferromagnetic spin-1 BEC exhibits a second-order gapless (quantum) phase transition due to a competition between the magnetic and collisional spin interaction energies. The dynamics of slow quenches through the critical point are predicted to exhibit universal power-law scaling as a function of quench speed. In spatially extended condensates, these excitations are revealed as spatial spin domains. In small condensates, the excitations are manifest in the temporal evolution of the spin populations, illustrating a Kibble-Zurek type scaling.\footnote{B. Damski and W. H. Zurek, Phys. Rev. Lett. 99, 130402 (2007)} We will present the results of our investigation and compare them to full quantum simulations of the system. [Preview Abstract] |
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D1.00025: Dissipation as a resource for atomic binding and crystallization Mikhail Lemeshko, Hendrik Weimer, Johannes Otterbach The formation of molecules and supramolecular structures results from bonding by conservative forces acting among electrons and nuclei and giving rise to equilibrium configurations defined by minima of the interaction potential. Here we show that bonding can also occur by the non-conservative forces responsible for interaction-induced coherent population trapping. The bound state arises in a dissipative process and manifests itself as a stationary state at a preordained interatomic distance. Remarkably, such a dissipative bonding is present even when the interactions among the atoms are purely repulsive. The dissipative bound states can be created and studied spectroscopically in present-day experiments with ultracold atoms or molecules and can potentially serve for cooling strongly interacting quantum gases [1]. An extension of this technique to a many-particle system (Bose-Einstein Condensate of Rydberg-dressed atoms) allows to observe long-range ordered crystalline structures emerging due to dissipation [2]. \\[4pt] [1] M. Lemeshko, H. Weimer, ``Dissipative binding of atoms by non-conservative forces'' Nature Communications 4, 2230 (2013)\\[0pt] [2] Johannes Otterbach, Mikhail Lemeshko, ``Long-Range Order Induced by Dissipation,'' arXiv:1308.5905 [Preview Abstract] |
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D1.00026: Radiative charge transfer in ultra-cold collisions of S with Protons P.C. Stancil, G. Shen, J.F. McCann, B.M. McLaughlin Molecule formation processes involving second-row elements is of prime interest as searches are ongoing in a variety of interstellar and circumstellar media [1]. We have investigated radiative decay processes at ultra-cold temperatures and above for S colliding with H$^+$. Previously [1], we have investigated this system for radiative association. We use the MOLPRO quantum chemistry suite of codes to obtain accurate potential energies and transition dipole moments as a function of internuclear distance between low-lying states of the SH$^+$ molecular ion complex. A multi-reference configuration-interaction (MRCI) approximation is used to determine all the potential energy curves and transition dipole moments, where the molecular orbitals (MO's) are obtained from state-averaged multiconfiguration-self-consistent-field (MCSCF) calculations. The collision problem is solved using a fully quantum-mechanical approach, an optical potential method, and a semiclassical approximation at higher energies. Rate coefficients are determined for temperatures ranging from micro-Kelvin up to 20,000 K. Further details and a comprehensive set of results will be presented. \\[4pt] [1] P. C. Stancil et al., Astron. Astrophys. Suppl. Ser. 143, 107 (2000). [Preview Abstract] |
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D1.00027: Feshbach Resonance Optimized Photoassociation Spectroscopy of Rb Sean Krzyzewski, Thomas Akin, James Dizikes, Michael Morrison, Eric Abraham We present preliminary results of an experiment to measure singly-excited molecular electronic potential curves of Rubidium using Feshbach optimized photoassociation. A Feshbach resonance is used to enhance the photoassociation signal by altering the initial scattering wave function, increasing the overlap with the final excited-state bound wave function. We focus on the purely triplet $0^-_g$ state of Rb$_2$ that connects asymptotically to the $5^2S_{1/2} + 5^2P_{1/2}$ separated-atoms limit, due to its simple electronic structure. We trap ultracold atoms undergoing photassociation with and without the presence of a Feshbach resonance. We provide absolute photoassociation rates into vibrational states of excited electronic states that are inaccessible with conventional spectroscopy using a close-coupled scattering calculation. We specifically investigate the dependence on magnetic field, frequency, and polarization. [Preview Abstract] |
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D1.00028: Isotope and vibrational excitation effects in ultracold chemical reactions Gagan B. Pradhan, N. Balakrishnan, Brian K. Kendrick We discuss the effect of vibrational excitation on chemical reaction between O($^1D$) and H$_2$ and OH+O at cold and ultracold temperatures. The effect of isotope substitution is investigated by exploring dynamics of O($^1D$)+D$_2$ reaction and comparing results against its H$_2$ counterpart. It is found that while vibrational excitation has a moderate effect on OH+O reaction, it has only marginal effect on O($^1D$)+H$_2$/D$_2$ reactions. For $v=2$ and $v=3$ of OH it is found that non-reactive relaxation pathway is dominated by a multi quantum process than a sequential single quantum pathway. Kinetic isotope effect is determined for the O($^1D$)+H$_2$/D$_2$ systems as the ratio of rate coefficients for H$_2$ and D$_2$ reactions and comparisons are made with available room temperature experimental data. [Preview Abstract] |
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D1.00029: Efficient Continuous-Duty Bitter-Type Electromagnets for Cold Atom Experiments Dylan Sabulsky, Paloma Ocola, Colin Parker, Nathan Gemelke, Cheng Chin We present the design, construction and characterization of Bitter-type electromagnets which can generate high magnetic fields under continuous operation with efficient heat removal for cold atom experiments. The electromagnets are constructed from a stack of alternating layers consisting of copper arcs and insulating polyester spacers. Efficient cooling of the copper is achieved via parallel rectangular water cooling channels between copper layers with low resistance to flow; a high ratio of the water-cooled surface area to the volume of copper ensures a short length scale $\sim$1 mm to extract dissipated heat. High copper fraction per layer ensures high magnetic field generated per unit energy dissipated. The ensemble is highly scalable and compressed to create a watertight seal without epoxy. From our measurements, a peak field of 770 G is generated 14 mm away from a single electromagnet with a current of 400 A and a total power dissipation of 1.6 kW. With cooling water flowing at 3.8 l/min, the coil temperature only increases by 7 degrees Celsius under continuous operation. [Preview Abstract] |
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D1.00030: Progress on the Creation of a High-Brightness Ba$^{+}$ Focused Ion Beam (FIB) Using Transverse Laser Cooling Truman Wilson, Jabez McClelland Focused ion beam (FIB) systems have a wide range of nanotechnology applications including high-resolution imaging and nanofabrication of materials. To meet a growing demand for improved FIB performance, new sources that take advantage of laser-cooling of atoms have recently been introduced. In this poster, I will present our progress towards the creation of a laser-cooled focused ion-beam source using $^{138}$Ba$^{+}$. Ba$^{+}$ is created by surface impact ionization of Ba vapor on a heated Ir target. These ions are then extracted to a region where we can apply laser light transverse to the direction of the ion beam propagation tuned to the Ba II cooling transitions at 493.4 nm and 649.9 nm. By laser cooling transverse to the ion beam, it should be possible to create a FIB source with a brightness that exceeds that of the Ga$^{+}$ source used currently for many nanotechnology applications. It may also be possible to counteract some of the heating effects of Coulomb interactions, allowing higher beam currents. If successful, this technique could open the possibility of a new class of FIB sources using ions that can be effectively laser-cooled. [Preview Abstract] |
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D1.00031: Analysis of Optical Bichromatic and Polychromatic Forces on Atoms and Molecules Leland Aldridge, Scott Galica, Tony Le, E.E. Eyler Previous work with optical bichromatic forces (BCFs) has demonstrated their ability to rapidly decelerate and cool atomic beams, and we have recently proposed extensions to molecules and multicolor beams.\footnote{M. A. Chieda and E. E. Eyler, Phys. Rev. A \textbf{84}, 063401 (2011); S. E. Galica, L. Aldridge, and E. E. Eyler, Phys. Rev. A \textbf{88}, 043418(2013).} We have performed extensive numerical simulations of bichromatic and polychromatic laser forces on a two-level system, including sensitivity to variations of parameters such as intensity, beam balance, and atomic velocity. We discuss progress on multi-level simulations, which are essential for designing optimal deceleration and cooling of molecules. We also discuss ongoing experimental tests of polychromatic forces on helium and of bichromatic forces on molecules, using the $B \leftrightarrow X$ transition in CaF as a test case. [Preview Abstract] |
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D1.00032: Precision spectroscopy of ultracold Sr$_2$ molecules in an optical lattice Geoffrey Iwata, Mickey McDonald, Bart McGuyer, Tanya Zelevinsky Trapped, ultracold $^{88}$Sr$_2$ continues to be a versatile tool to probe quantum molecular dynamics and study fundamental interactions. Here we overview recent precision experiments carried out in an optical lattice that build on previous work, including measurements of Coriolis mixing of molecular states via anomalous Zeeman shifts, magnetic-field enabled electric-dipole transitions with $\Delta J > 1$, and the observation of doubly forbidden M1 and E2 transitions. Exploiting the tensor lattice light shift, we engineer molecular magic wavelengths and magnetic sublevel mixing for precision spectroscopy. These studies provide a basis to test and develop \textit{ab~initio} models for molecular quantum chemistry and many-body physics. Progress towards production of deeply bound ground-state $^{88}$Sr$_2$ is described. [Preview Abstract] |
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D1.00033: A Magneto-Optical Trap for Diatomic Molecules Mark Yeo, Matthew Hummon, Alejandra Collopy, Benjamin Stuhl, Boerge Hemmerling, Eunmi Chae, Garrett Drayna, Aakash Ravi, Maximilian Kuhnert, Maurice Petzold, John Doyle, Jun Ye The magneto-optical trap (MOT) has long been the workhorse for atomic physics and is a powerful technique to rapidly produce ultracold, dense samples of atoms. Extending this technique to produce cold, dense samples of a diverse set of molecules will revolutionize the study of strongly interacting quantum systems, precision measurement and physical chemistry. In this work, we will report on progress towards the realization of a 3 dimensional MOT for the polar molecule YO. We are implementing a chirped frequency laser slowing scheme, where the buffer gas cooled molecules are slowed to a trappable velocity of 10 m/s. The 3D trapping is generated with a quasi-cycling transition and an oscillating quadrupole magnetic field. [Preview Abstract] |
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D1.00034: Alignment of D-state Rydberg molecules Robert L\"ow, Alexander Krupp, Anita Gaj, Jonathan Balewski, Philipp Ilzh\"ofer, Sebastian Hofferberth, Markus Kurz, Peter Schmelcher, Tilman Pfau For highly excited Rydberg atoms with principal quantum numbers n $\sim$ 40, single ground state atoms can be trapped in the potential created by the Rydberg electron, leading to so called trilobite Rydberg molecules. Until now mostly S-states have been studied in terms of lifetime, coherence properties, dimers, trimers and polymers, permanent electric dipole moments, etc. Recently we have extended this class of molecules by D-state molecules offering more complex azimuthal structures. By choosing various magnetic substates, well separated by a magnetic offset field, we are able to address specific ro-vibronical states. A peculiar property of our excitation scheme is that the resulting Rydberg molecules are excited to stationary states with a high degree of alignment or anti-alignment. [Preview Abstract] |
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D1.00035: 2D Skyrmion Crystal and Gauge Field for Neutral Atoms in Magnetic Lattices Jeong Ho Han, Moosong Lee, Min-seok Kim, Jae-yoon Choi, Yong-il Shin We describe a scheme to realize two-dimensional Skyrmion crystals for neutral atoms using magnetic lattices. Hexagonal magnetic lattices are generated from current-carrying wires arranged in triangular lattice configurations and an external bias field normal to the lattice plane. We show that real-space Skyrmion-lattice spin textures can be imposed on spinor condensates with the magnetic lattices and that one can achieve large effective magnetic flux per unit cell from the spin texture control [1]. We discuss on the experimental conditions to study Haldane model and possible topological phases in this scheme. \\[4pt] [1] J. Choi \textit{et al}., Phys. Rev. Lett 111, 245301 (2013) [Preview Abstract] |
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D1.00036: Fractional Quantum Hall Physics with Rotating Bose Gases Louis Jacome, Jianshi Zhao, Nathan Gemelke Fractional quantum Hall (FQH) physics familiar in two-dimensional electron systems has also been predicted to appear in a gas of interacting bosons that are confined to a rapidly rotating trap. Previous experiments in an optical lattice with rotating lattice sites observed strong correlations in large ensembles of few-body clusters consistent with a bosonic analog of fractional hall states, but the large dispersion in particle number prevented unambiguous interrogation of specific states' properties. We describe a new generation of experiments with a single-site-resolved optical microscope and Rubidium-87 atoms, which allows for occupancy resolved measurements. Details of the apparatus, including the high numerical-aperture (NA=0.8) microscope, extension to new atomic isotopes with Feshbach-tuned interactions, and new techniques to probe FQH ground state properties will be discussed. Further extensions using impurity atoms as probes may allow for observation of the analog of fractionalized charge and possibly even fractionalized exchange statistics. [Preview Abstract] |
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D1.00037: Optical cooling of AlH$^+$ to the rotational ground state Chien-Yu Lien, Christopher Seck, Brian Odom We demonstrate cooling of the rotational degree of freedom of trapped diatomic molecular ions to the rotational ground state. The molecule of interested, AlH$^+$, is co-trapped and sympathetically cooled with Ba$^+$ to milliKelvin temperatures in its translational degree of freedom. The nearly diagonal Franck-Condon-Factors between the electronic X and A states of AlH$^+$ create semi-closed cycling transitions between the vibrational ground states of X and A states. A spectrally filtered femtosecond laser is used to optically pump the population to the two lowest rotational levels, with opposite parities, in as fast as 100 $\mu$s via driving the A-X transition. In addition, a cooling scheme relying on vibrational relaxation brings the population to the $N=0$ positive-parity level in as fast as 100 ms. The population distribution among the rotational levels is detected by resonance-enhanced multiphoton dissociation (REMPD) and time-of-flight mass-spectrometry (TOFMS). Although the current two-photon state readout scheme is destructive, a scheme of single-molecule fluorescence detection is also considered. [Preview Abstract] |
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D1.00038: ATOMIC AND MOLECULAR STRUCTURE AND PROPERTIES |
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D1.00039: High precision variational calculations of non-relativistic energy levels of the hydrogen molecular ion Ye Ning, Zongchao Yan We have performed a benchmark calculation of non-relativistic energy level of H$_{2}^{+}$, using Hylleraas coordinates [1] containing three non-linear parameters so that three inter-particle radial coordinates $r_1$, $r_2$, and $r_{12}$ can be described independently. Rayleigh-Ritz variational principle is used to find out minimum of the expectation value of Hamiltonian of this system. Configuration of base varies according to the total angular momenta $J$ of the system, the bigger $J$ is, the more blocks are needed. To solve the matrix equation, power method is used to identify the ground state as well as some other excited states. The non-relativistic ground state energy of H$_{2}^{+}$ has been calculated to a few parts in 10$^{33}$, which represents the best energy level reported so far. \\[4pt] [1] M. M. Cassar and G. W. F. Drake, \textit{J. Phys. B.} \textbf{37} 2485 (2004) [Preview Abstract] |
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D1.00040: Role of d$^{\mathrm{n-1}}$s configurations in hyperfine structure (hfs) of d$^{\mathrm{n}}$ levels in transition metal atoms and ions: Application to V II Donald Beck, Marwa Abdalmoneam Independent particle calculation of the hfs of d$^{\mathrm{n}}$ levels in transition metal atoms can lead to serious errors when there are nearby d$^{\mathrm{n-1}}$s levels. These errors can only be corrected when the latter levels are properly mixed into the d$^{\mathrm{n}}$ wave-functions along with, e.g. the usual hfs single excitations [1]. Recently hfs of 25 V II levels has been measured [2] and there is substantial disagreement with 4 of 8 previously measured hfs [3]. Preliminary RCI calculations [4] support the newer work [2].\\[4pt] [1] D.R. Beck, Phys.Rev. A45,1399 (1992).\\[0pt] [2] N.M.R. Armstrong et al, Phys.Scr.84,055301 (2011).\\[0pt] [3] K. Arvidsson, M.S. thesis, Lund Observatory (2003).\\[0pt] [4] M. Abdalmoneam and D.R. Beck, manuscript in preparation. [Preview Abstract] |
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D1.00041: Use of Broadened Diode Lasers to Enhance Optical Pumping of Alkali Metals Eric Litaker, Munir Pirbhai, Dale Tupa, Timothy Gay We have made a systematic study of rubidium optical pumping using an amplified tunable diode laser which has been incrementally broadened in order to determine the effect of linewidth broadening on rubidium polarization. We vary the frequency of the circularly-polarized laser across the D$_{\mathrm{1\thinspace }}$transition absorption profile for each of four linewidths (unbroadened (.01 MHz), .5 MHz, 2 GHz, and 8 GHz) and measure the rubidium polarization using Faraday rotation. The rubidium number density is on the order of 10$^{\mathrm{12\thinspace }}$cm$^{\mathrm{-3}}$, with 1 Torr of N$_{\mathrm{2\thinspace }}$as the buffer gas. These results are then compared with polarization measurements taken using a re-pump laser tuned to the rubidium D$_{\mathrm{2}}$ transition, and with theoretical calculations of the rubidium polarization. [Preview Abstract] |
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D1.00042: Ultrafast Electron Diffraction from Laser-Aligned CS$_{2}$ Molecules Jie Yang, Christopher Hensley, Martin Centurion Electron diffraction from laser-aligned molecules is a powerful method for studying molecular structure and dynamics. In this method, the molecular structure and angular distribution can be measured simultaneously from a single diffraction pattern. We have used ultrafast electron diffraction to study the structure and dynamics of impulsively laser-aligned carbon disulfide (CS$_{2})$ molecules. The experimental data shows that the degree of alignment saturates for a laser fluence of 0.8 J/cm$^{2}$, which is in disagreement with simulations. This could be due to the excitation of vibrational modes in the molecule. We have also observed that the saturation depends not only on the fluence but also on the pulse duration, and that the angular distribution continues to change after the saturation. From the diffraction patterns at peak alignment and the revival structure, we have concluded that there is no major deformation, such as bending excitation, in molecular structure. Moreover, no significant dissociation is observed until the intensity reaches 3X10$^{13}$W/cm$^{2}$. [Preview Abstract] |
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D1.00043: New Spectroscopic Data and Analysis of Existing Data on the $A^{1}\Sigma^{+}$ and $b^{3}\Pi$ states of NaK T. Bergeman, H. Salami, Kara Richter, Joshua Jones, Amanda Ross Current efforts to produce cold NaK molecules\footnote{M. Zwierlein, private communication.} by excitation from Feshbach resonance states and stimulated decay require an accurate model of the energy level structure of the species. There have been numerous publications over the past 25 years with high quality spectroscopic data, but gaps remain, and there is no systematic compilation for the NaK A and b states. We have obtained new data that fill some of the gaps and provide more information on perturbation interactions between these states, and we have constructed a model based on direct fits to potentials and spin-orbit coupling elements. We will present results and discuss possible interactions with the NaK $c^{3}\Sigma^{+}$ state. [Preview Abstract] |
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D1.00044: Analysis of Data on the $B^{1}\Pi$ and $c^{3}\Sigma^{+}$ States of NaK T. Bergeman, H. Salami, Amanda Ross Current efforts to produce cold NaK molecules from cold atoms start with production of Feshbach resonances [1] followed by excitation to high-lying singlet or triplet states, and then one- or two-step possibly stimulated decay to $v$=0 of the $X$ ground state. Efficient use of these processes requires an accurate and detailed knowledge of NaK energy level structure. There have been numerous reports of excellent spectroscopic data on the NaK $B$ and $c$ states of Nak, as summarized in [2]. To meet requirements of current applications for a detailed, accurate compilation, we have constructed a model based on direct fits of experimental term values to potentials and spin-orbit coupling functions. Identification of regions of singlet-triplet $B-c$ state mixing is especially useful for current work. \\[4pt] [1] C.-H. Wu, M. Zwierlein, et al., PRL {\bf 109}, 085301 (2012). \\[0pt] [2] R. Ferber et al., JCP {\bf 112}, 5740 (2000). [Preview Abstract] |
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D1.00045: New \emph{ab initio} potential curves for the ground and low-lying excited states in NaCa$^+$ and LiBe$^+$ molecular ions Di Shu, Sandipan Banerjee, John A. Montgomery Jr., Robin C\^ot\'e We report new accurate \emph{ab initio} calculations for the ground and low-lying excited states in NaCa$^+$ molecular ion and the lowest singlet and triplet states in LiBe$^+$. Preliminary results of the corrections due to the nuclear hyperfine interactions in the lowest singlet and triplet states for NaCa$^+$ are also reported. The \emph{ab initio} calculations were performed using valence multireference configuration interaction (MRCI) with complete active space self consistent field (CASSCF) orbitals. [Preview Abstract] |
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D1.00046: Atomic Properties of Superheavy Elements No, Lr, and Rf Marianna Safronova, Vladimir Dzuba, Ulyana Safronova The study of the superheavy elements (nuclear charge Z $>$ 100) is an important multidisciplinary area of research involving nuclear and atomic physics and chemistry. Atomic calculations help to understand the role of the relativistic and many-body effects and provide important information for the planning and interpreting the measurements. The need to treat relativistic and correlation effects to high level of accuracy makes the calculations a very challenging task. In this work, the combination of the configuration interaction technique and all-order linearized coupled-cluster method is used to calculate excitation energies, ionization potentials, and static dipole polarizabilities of superheavy elements nobelium, lawrencium and rutherfordium. Breit and QED corrections are also included. The same calculations are carried out for similar but lighter elements Hf, Lu, and Yb where experimental data are available to test the accuracy of the calculations. [Preview Abstract] |
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D1.00047: Current Status of Atomic Spectroscopy Databases at NIST Alexander Kramida, Yuri Ralchenko, Joseph Reader NIST's Atomic Spectroscopy Data Center maintains several online databases on atomic spectroscopy. These databases can be accessed via the http://physics.nist.gov/PhysRefData web page. Our main database, Atomic Spectra Database (ASD), recently upgraded to v. 5.1, now contains critically evaluated data for about 215,000 spectral lines and 107,000 energy levels of almost all elements in the periodic table. This new version has added several thousand spectral lines and energy levels of Ca III, Mn II, Fe II, Co II, Ag II, and In II. Most of these additions contain critically evaluated transition probabilities important for astrophysics, technology, and fusion research. The ASD tables of ground states and ionization energies of all elements up to Ds ($Z=$110) in all ionization stages are currently being re-evaluated, updated, and extended with results of our new relativistic calculations. We continue maintaining and regularly updating our bibliography databases, ensuring comprehensive coverage of current literature on atomic spectra, including energy levels, spectral lines, transition probabilities, hyperfine structure, isotope shifts, Zeeman and Stark effects. Our other popular databases, such as the Handbook of Basic Atomic Spectroscopy Data, searchable atlases of spectra of Pt-Ne and Th-Ne lamps, and non-LTE plasma-kinetics code comparisons, continue to be maintained. [Preview Abstract] |
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D1.00048: Critical Nuclear Charge of the Quantum Mechanical Three-Body Problem Michael Busuttil, Amirreza Moini, Gordon W.F. Drake The critical nuclear charge ($Z_c$) for a three-body quantum mechanical system consisting of positive and negative charges is the minimum nuclear charge that can keep the system in a bound state. Here we present a study of the critical nuclear charge for two-electron (heliumlike) systems with infinite nuclear mass, and also a range of reduced mass ratio ($\mu/m$) up to 0.5. The results help to resolve a discrepancy in the literature for the infinite mass case, and they are the first to study the dependence on reduced mass ratio. It was found that $Z_c$ has a local maximum with $\mu/m=0.352\:5$. The critical charge for the infinite mass case is found to be $Z_c = 0.911\:028\:224\:076\:8(1\:0)$. This value is more accurate than any previous value in the literature [1, 2, 3, 4], and agrees with the upper bound $Z_c=0.911\:03$ reported by Baker et al.\ [1]. The critical nuclear charge outside this range [0.5 -- 1.0] still needs to be investigated in future works.\\[4pt] [1] J. D. Baker et al.\ Phys.\ Rev.\ A {\bf 41}, 1247 (1990).\newline [2] N. L. Guevara and A. V. Turbiner. Phys.\ Rev.\ A {\bf 84}, 064501 (2011).\newline [3] F. H. Stillinger Jr.\ J. Chem.\ Phys.\ {\bf 45}, 3623 (1966).\newline [4] G. A. Arteca et al.\ J. Chem.\ Phys.\ {\bf 84}, 1624-1628 (1986). [Preview Abstract] |
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D1.00049: An x-ray probe of nickel nanoparticles generated by laser ablation C.S. Lehmann, G. Doumy, S.H. Southworth, A.M. March, A.D. DiChiara, Y. Gao, E.P. Kanter, B. Kr\"assig, D. Moonshiram, L. Young, K.W. Chapman, P.J. Chupas A plume of nickel atoms and nanoparticles can be generated by an intense laser pulse hitting a solid nickel surface. We set up a Ni ablation source in a vacuum chamber on an x-ray beamline at the Advanced Photon Source and used x-ray absorption, x-ray emission, and ion spectroscopies to probe the ablation plume at x-ray energies above the Ni \textit{K}-edge at 8.33 keV. The laser and x-ray pulses were overlapped in time and space with variable delay to measure the time evolution of the ablation plume. Measurements of the charge states produced by x-ray absorption were not possible due to the intense prompt ions ejected in the ablation process. However, Ni \textit{K}$\alpha$ x-ray emission was measured as functions of laser fluence and pump-probe delay. The fluorescence yield was also used to record the near-edge x-ray absorption spectrum of the nanoparticles in the plume. The nanoparticles were collected and their diameters were determined to be $\sim$9 nm from x-ray scattering pair-distribution-function measurements. The experiments demonstrate the use of x-ray techniques to characterize laser ablation processes. [Preview Abstract] |
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D1.00050: Electronic Transitions and Bandhead fitting for $^{130}$Te$_{2}$ from 664 to 676THz David La Mantia The electronic spectra of $^{130}\rm{Te}_{2}$ serves as a wavelength standard for many spectroscopy investigations. The molecule is also of interest for a new gain medium for optically pumped lasers, as well as relativistic investigations of large spin-orbit coupling. We scanned the molecule in the region 664 to 676 THz to create an atlas of transition lines, in line with the previous investigations of $Cariou,\hspace*{1 mm}et\hspace*{1 mm}al$.\footnote{Cariou, J. and Luc, P. ``Atlas Du Spectre D'Absorption De La Molecule De Tellure.'' Laboratoire Aime, Cotton CNRS II 91405 Orsay, France. 1980.} The BO$^{+}_{u}\leftarrow XO^{+}_{g}$ transition was studied in great detail using the precise data for the $X$ band from $Verges,\hspace*{1 mm}et\hspace*{1 mm}al.\hspace*{1 mm}$\footnote{Verges, J. ``The Laser Induced Fluorescence Spectrum of Te$_{2}$ Studied by Fourier Transformation Spectrometry.'' \textit{Physica Scripta}. Vol.25, 338-350, 1982} Using this data, the number of vibrational bandheads was identified allowing the rotational parameters B, D and H to be precisely obtained for each bandhead. These results are combined to obtain the appropriate spectroscopic parameters for the $B_{0}$ electronic band. The results of this investigation will be presented. [Preview Abstract] |
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D1.00051: Dipole and Quadrupole Polarizabilities of Ni II and Parameters of an Effective Potential for Ni I Rydberg States Marwa Abdalmoneam, Donald Beck The Relativistic Configuration Interaction Method has been used to evaluate the dipole and quadrupole polarizabilities of Ni II with the results (for 3d$^{9} \quad^{2}$D$_{3/2})$ of 7.686 au and (for 3d$^{9} \quad^{2}$D$_{5/2})$ 62.94 au respectively. The experimental value for the latter is estimated [2] to be 55(8) au. Our result for the non-adiabatic scalar dipole polarizability ($^{2}$D$_{5/2})$ is 9.243 au (experimental estimate [2] 8.9(1.2) au) and for the off-diagonal tensor dipole polarizability ($^{2}$D$_{5/2})$ 0.220 au (experimental estimate [2] -0.04 au). Significant cancelations occur here [1].\\[4pt] [1] Dipole and Quadrupole Polarizabilities of Ni II and Parameters of an Effective Potential for Ni I Rydberg States, J.Phys.B., submitted for publication.\\[0pt] [2] S L Woods and S R Lundeen, Phys. Rev. A85, 042505 (2012). [Preview Abstract] |
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D1.00052: Pump-probe transmission spectra in the general cases of arbitrary polarizations and powers of probe and pump beams of $^{85}$Rb atom Hafeez Rehman, Adnan Muhammad, Heung-Ryoul Noh, Jin-Tae Kim We have investigated profile variations of probe beam transmission signals from hyperfine levels between the ground 5 $S_{1/2}$ and excited 5 $P_{3/2}$ lines of $^{85}$Rb atom in a vapor cell with degenerate magnetic sublevels with respect to changes of polarizations, powers, beam sizes, and directions of control and probe beams. The probe laser frequency is fixed at the F'' $=$ 3 $\to $ F' $=$ 4 degenerate two level system of $^{85}$Rb atom while the control beam is scanned through F'' $=$ 2 and 3 $\to $ F'' $=$ 1, 2, 3, and 4 hyperfine manifold. Various polarization dependent profiles in the transmission signals including EIT-like and EIA signals have been observed. The observed signal profiles are compared with signals calculated from generalized time-dependent density matrix equations considering multi-photon processes between the degenerate magnetic sublevels and match well with the calculated signal profiles. [Preview Abstract] |
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D1.00053: Spectroscopic analysis on the 5 $^{1}\Sigma_{0}^{+}$, 3 $^{1}\Pi _{1}$, 5 $^{3}\Sigma_{1}^{+}$, and 4 $^{3}\Pi_{1}$ states of the KRb diatomic molecule using a molecular beam Yonghoon Lee, Bongsoo Kim, Jin-Tae Kim The 5 $^{1}\Sigma^{+}$, 3 $^{1}\Pi $, 5 $^{3}\Sigma_{1}^{+}$, and 4 $^{3}\Pi_{1} \quad \leftarrow \quad X \quad^{1}\Sigma^{+}$ (v'' $=$ 0, 1) states of the KRb diatomic molecule near 440 nm have been identified using mass-resolved resonance enhanced two-photon ionization (RE2PI) in a cold molecular beam. For the 3 $^{1}\Pi $ state, the electronic term values ($T_{e})$ and vibrational constants are determined. From a rotational contour analysis, the $\Omega $ symmetries of the upper electronic states of the observed bands are assigned. Vibrational numberings of the experimentally observed levels of the 5 $^{1}\Sigma^{+}$, 3 $^{1}\Pi $, 5 $^{3}\Sigma_{1}^{+}$ and 4 $^{3}\Pi_{1}$ states, are also assigned. The fitted perturbation constants such as spin-orbit coupling matrix element, rotational temperature, linewith, $T_{v}$, and rotational constants have been determined and used to know line profiles of the rotational spectra. [Preview Abstract] |
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D1.00054: Spectroscopy of Potassium Rydberg States via Electromagnetically Induced Transparency Wenchao Xu, Brian DeMarco We perform precision spectroscopy of potassium Rydberg states in a heated vapor cell. The transition frequencies are obtained by observing electromagnetically induced transparency (EIT) features in a two-photon process: $4S_{1/2} \rightarrow 5P_{3/2} \rightarrow nS_{1/2}$. We use a velocity selective optical pumping scheme to overcome Doppler broadening, which would suppress the EIT signal since the probe frequency is larger than the coupling frequency. Such precise spectroscopy will enable novel experiments with Rydberg-dressed ultracold Fermi gases. [Preview Abstract] |
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D1.00055: Contribution of the $4f$-core-excited states in determination of atomic properties in the Promethium Isoelectronic Sequence Peter Beiersdorfer, U.I. Safronova, A.S. Safronova The atomic properties of Pm-like ions were comprehensively studied using relativistic atomic codes with the main emphasis on W ion. Excitation energies of the $4f^{14}nl$ (with $nl$ = $5s$, $6s$, $5p$, $6p$, $5d$, $6d$, and $5f$) states in Pm-like ions with nuclear charge $Z$ ranging from 74 to 100 are evaluated within the framework of relativistic many-body theory (RMBPT). First- and second-order Coulomb energies and first- and second-order Breit corrections to the energies are calculated. The important question of what is the ground state in Pm-like ions was answered. Properties of the $4f$-core-excited states are evaluated using the multiconfiguration relativistic Hebrew University Lawrence Livermore Atomic Code (HULLAC code) and the Hartree-Fock-Relativistic method (COWAN code). Our large scale calculations includes the following set of configurations: $4f^{14}5s$, $4f^{14}5p$, $4f^{13}5s^2$, $4f^{13}5p^2$, $4f^{13}5s5p$, $4f^{12}5s^25p$, $4f^{12}5s5p^2$, and $4f^{12}5p^3$. Excitation energies, transition rates, and lifetimes in Pm-like tungsten are evaluated with additional inclusion of the $4f^{11}5s^25p^2$, $4f^{11}5s5p^3$, $4f^{10}5s^25p^3$, and $4f^{10}5s5p^4$ configurations. Wavelengths of the $5s-5p$ transitions are obtained by the COWAN, HULLAC, and RMBPT codes. [Preview Abstract] |
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D1.00056: Determination of the neon double core hole lifetime using high-intensity x-rays from the LCLS B. Kr{\"a}ssig, E.P. Kanter, G. Doumy, A.M. March, S.H. Southworth, L. Young, J.D. Bozek, C. Bostedt, M. Messerschmidt The concentration of x-ray photons in a focussed radiation pulse at the SLAC Linac Coherent Light Source (LCLS) exposes atoms to multiple sequential photoabsorption processes [1]. For $\sim$keV x rays the absorption in neon targets primarily the 1s shell and hollow neon atoms are readily created when the rate of photoabsorption exceeds that of inner-shell decay. With typical LCLS parameters and a $\sim$1 micron focus, we observed double core-hole states in neon for up to $\sim$20\% of 1s ionization events. For comparison, electron-electron correlations lead to double-to-single core-hole ratios of just 0.3\% under single photon absorption conditions [2]. Using the high-resolution electron time-of-flight spectrometers of the LCLS AMO Physics end station, we measured the Ne {\em KK-KLL} Auger hypersatellite spectrum and determined the lifetime of the Ne$^{2+}$(1s$^{-2}$) doubly core-excited state. The results are compared to theoretical predictions. \\[4pt] [1] L. Young {\em et al.}, Nature {\bf 466}, 56 (2010). \par\noindent [2] S. H. Southworth, {\em et al.} Phys. Rev. A {\bf 67}, 062712 (2003). [Preview Abstract] |
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D1.00057: Multiply-ionized Atoms at Low Energy for Precise Measurements Shannon Fogwell Hoogerheide, Joseph N. Tan Recent work at NIST introduced a new system for the slowing, capture and manipulation of multiply-ionized atoms in a controlled environment suitable for precision measurements. As a demonstration of its potentials, we have measured the lifetimes of metastable states in krypton and argon (gases), and are now extending this technique to metals such as iron. Work is also underway on a table-top apparatus that incorporates a miniature electron-beam ion trap (EBIT) coupled to a cryo-cooled, compact Penning trap to enable spectroscopic studies of interest for atomic physics, astrophysics, and metrology. This apparatus will allow charge exchange between laser-excited Rydberg rubidium atoms and isolated bare nuclei, opening the way for precision spectroscopy of one-electron ions in Rydberg states using optical frequency comb technology. Earlier theoretical work at NIST has shown that such measurements would provide a new determination of the Rydberg constant that was independent of the proton radius. Such a measurement could help resolve the proton-radius puzzle. Additional applications could include the study of very-long-lived atomic states proposed for new atomic frequency standards or laboratory studies of potential time variation of the fine structure constant. [Preview Abstract] |
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D1.00058: Ongoing Atomic Physics Research at the NIST EBIT in the EUV and X-ray Regimes Yuri Podpaly, John Gillaspy, Joseph Reader, Yuri Ralchenko We present an overview of recent work performed at the NIST electron beam ion trap, EBIT, facility. The EBIT uses an electromagnetic trap and a precise electron beam, which can be tuned to maximize the production of a desired ionization stage, to confine and study highly charged ions. Recent interest in extreme ultraviolet (EUV) lithography light sources has led to more research into radiation from highly charged rare-earth elements. In this work, we extend that research to Rb-like to Ni-like erbium and Kr-like to Ni-like samarium n$=$4-n$=$4 transitions in the 3-20 nm range. Overall, 61 lines (55 new) of samarium and 56 lines (51 new) of erbium were identified with individual uncertainties determined for each line (most in the 0.001 nm range). Large-scale collisional radiative modeling was used for line identifications. Ongoing work in the x-ray regime for diagnostics of fusion-type plasmas will also be shown. [Preview Abstract] |
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D1.00059: A New Echelle Spectrometer for Measuring UV Branching Fractions of Fe-group Ions Michael Wood, James Lawler Unexpected trends in relative Fe-group abundances are observed in old, metal-poor stars which may offer insights into the history of nucleosynthesis in the Galaxy. Abundances are traditionally derived using lines in the neutral species, though Fe-group elements are predominately singly-ionized in the photospheres of stars of interest. Using weak UV lines connected to the ground and low metastable levels of Fe-group ions eliminates errors associated with departures from LTE, resulting in more accurate abundances. A new echelle spectrograph combined with an aberration corrected cross dispersion system has been developed to measure accurate branching fractions for these UV lines. This instrument is capable of recording spectra at high resolving power with very broad wavelength coverage. The instrument is also free from the multiplex noise of a FTS, making it ideal for measuring branching fractions of weak lines. These branching fractions are combined with published radiative lifetimes to produce accurate transition probabilities for UV lines connected to the ground and low metastable levels of singly-ionized Fe-group elements. Instrument design and recent results will be highlighted. [Preview Abstract] |
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D1.00060: Temporal Distributions of Optical Energy Transitions and Photoluminescence Quenching in CuInS2 with ZnS Capping and Alloy Quinton Rice, Sangram Raut, Wan-Joong Kim, Ryan Rich, Rafal Fudala, Mahmoud Abdel-Fattah, Bagher Tabibi, Ignacy Gryczynski, Zygmunt Gryczynski, Sungsoo Jung, Jaetae Seo The semiconductor nanocrystals of CuInS$_{2}$ are of great interest for optoelectronic and biomedical applications, because of no intrinsic toxicity related to the heavy metals of cadmium or lead chalcogenide nanomaterials, large tunability, and high color purity. The photonic energy evolution of CuInS$_{2}$ quantum dots includes surface-trapped state recombination and defect-related donor-acceptor transition. The interface defect states of CuInS$_{2}$/ZnS and quantum confinement modification of ZnCuInS$_{2}$ adjust the temporal evolution of photonic transitions. The temporal evolution of shorter lifetime at surface-trapped states or interface states and longer lifetime at intrinsic defect-related states are widely distributed with relative distinct probabilities through the entire PL spectral region. The temperature-resolved PL reveals that the surface or interface-trapped electrons are thermally active even at low temperatures, but the electrons at intrinsic defect-related states are relatively stable. Acknowledgement: The work at HU is supported by NSF HRD-1137747 and ARO W911NF-11-1-0177. [Preview Abstract] |
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D1.00061: Efficient three-photon excitation of quasi-1D $n\sim300$ strontium Rydberg atoms Xinyue Zhang, Shuzhen Ye, F. Barry Dunning, Shuhei Yoshida, Moritz Hiller, Joachim Burgd\"{o}rfer The production of high $n$, $n\sim300$, quasi-one-dimensional (quasi-1D) strontium Rydberg atoms via three-photon excitation of extreme Stark states in the presence of a weak dc field is explored. The experimental data are analyzed with the aid of classical trajectory Monte Carlo simulations and quantum calculations using a two-active-electron model. The results demonstrate that strongly-polarized quasi-1D states can be generated with much higher production rates than achieved using two-photon excitation. Furthermore, the data suggest that densities approaching those at which blockade effects become important might be realized opening up the opportunity to examine the behavior of strongly-coupled Rydberg atom pairs. [Preview Abstract] |
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D1.00062: Characterizing high-$n$ quasi-one-dimensional strontium Rydberg atoms Moritz Hiller, Shuhei Yoshida, Joachim Burgd\"{o}rfer, Shuzhen Ye, Xinyue Zhang, F. Barry Dunning The production of high-$n$, $n\sim300$, quasi-one-dimensional strontium Rydberg atoms by two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The polarization of the product states is probed using three independent techniques which are analyzed with the aid of classical-trajectory Monte Carlo simulations that employ initial ensembles based on quantum calculations using a two-active-electron model. Comparisons between theory and experiment demonstrate that the product states have large dipole moments, $\sim1.0-1.2n^2$ $a.u.$ and that they can be engineered using pulsed electric fields to create a wide variety of target states. [Preview Abstract] |
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D1.00063: A new simple exotic atom, $H^{-+}$: $e^{+}$ bound to $H^{-}$ in an atomic state I. Guevara, M. Weel, M.C. George, E.A. Hessels, C.H. Storry A beam of $H^-$ ions is directed along the axis of a solenoidal magnet winding. Within this magnet, cylindrical electrodes with applied potentials slow the ions to an energy of $\sim$ 50 eV in a magnetic field of $\sim$ 0.13 Tesla. This apparatus also acts as a charged particle trap. $e^+$ from a radioactive source are slowed in frozen neon, guided by magnetic fields and captured in this Surko-style accumulator with $\sim 10^7$ $e^+$ trapped and cooled for experiments. $H^-$ ions are directed through these e+ producing long-lived $H^{-+}$ atoms. $H^{-+}$ is not bound in the charged particle trap and continues with the initial momentum of the $H^-$ ion into a metal plate. Upon impact the $e^+$ quickly annihilates into back-to-back gammas. Detection of these coincident gammas indicates $H^{-+}$ that traveled the 2 meter to the detector and indicates a survival time of $\sim 5\mu s$. Typically systems with antimatter bound to matter particles have short lifetimes (and hence wide transition widths) due annihilation. Rydberg states of $H^{-+}$, however, have the long radiative lifetimes of normal matter atoms because there is little overlap of the $e^+$ wavefunction with the core. The detected rates or $H^{-+}$ are consistent with those expected for radiative recombination. [Preview Abstract] |
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D1.00064: MATTER WAVE INTERFEROMETRY |
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D1.00065: Interferometry with Strontium Ions Jarom Jackson, Enoch Lambert, Nils Otterstrom, Tyler Jones, Dallin Durfee We describe progress on a cold ion matter-wave interferometer. Cold Strontium atoms are extracted from an LVIS. The atoms will be photo-ionized with a two-photon transition to an auto-ionizing state in the continuum. The ions will be split and recombined using stimulated Raman transitions from a pair of diode lasers injection locked to two beams from a master laser which have been shifted up and down by half the hyperfine splitting. We are developing laser instrumentation for this project including a method to prevent mode-hopping by analyzing laser frequency noise, and an inexpensive, robust wavelength meter. [Preview Abstract] |
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D1.00066: Applied Atom Interferometry: On the Fringe Akash Rakholia, Hayden McGuinness, Grant Biedermann We demonstrate a dual-axis accelerometer and gyroscope atom interferometer via cold ensemble exchange [1]. The apparatus is capable of operating in a dynamic environment, due to the short time-of-flight $T \approx 4~\mathrm{ms}$ [2], with sensitivities at $\mathrm{\mu g/\sqrt{Hz}}$ and $\mathrm{\mu rad/s/\sqrt{Hz}}$ levels. Part of the sensitivity losses are mitigated due to operation at a high data-rate [3]. We explore various limitations to operation in a dynamic environment and enhancement of dynamic range using auxiliary sensors.\\[4pt] [1] A. V. Rakholia, H. J. McGuinness, G. W. Biedermann, ``Dual-axis, high data-rate atom interferometer via ensemble exchange,'' \emph{In Preparation}.\\[0pt] [2] D. L. Butts, J. M. Kinast, B. P. Timmons, and R. E. Stoner, J. Opt. Soc. Am. B 28, 416 (2011)\\[0pt] [3] H. J. McGuinness, A. V. Rakholia, and G. W. Biedermann, Appl. Phys. Lett. 100, 011106 (2012). [Preview Abstract] |
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D1.00067: Using an Atom Interferometer to Measure Changes in Tune-Out Wavelength caused by Rotation and Acceleration Raisa Trubko, James Greenberg, Michael T. St. Germaine, Maxwell D. Gregoire, Ivan Hromada, William F. Holmgren, Alexander D. Cronin Measurements of tune-out wavelengths made with an atom interferometer are shown to change by 150 pm due to inertial displacements. Because tune-out wavelengths can be measured with picometer precision in our laboratory, we explore how to use shifts in tune-out wavelengths to measure rotation rates with respect to an inertial frame. For example, measuring the earth's rotation rate with an uncertainty of 1{\%} appears possible with this technique. The origin of shifts in measured tune-out wavelengths ($\lambda _{zero,\, lab})$ as compared to tune-out wavelengths in an inertial frame ($\lambda_{zero})$ is explained by dispersive inertial phase shifts, the vector dynamic polarizability $\alpha^{v}(\omega )$, and dispersion compensation. An atom beam with a velocity spread and an ensemble of atomic spin states is required. Because accurate measurements of $\lambda _{zero}$ can be used for reporting ratios of dipole matrix elements, we also discuss methods for reducing systematic errors in measurements of $\lambda_{zero}$. [Preview Abstract] |
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D1.00068: Construction of next generation Yb Bose-Einstein condensate interferometer Benjamin Plotkin-Swing, Alan Jamison, Anupriya Jayakumar, Katherine McAlpine, Brendan Saxberg, Ryan Weh, Subhadeep Gupta We are building a new apparatus for interferometry using Yb Bose-Einstein condensates. In our first generation contrast interferometer we measured h/m, where h is Planck's constant and m is the mass of an ytterbium atom, in order to determine the fine structure constant $\alpha$. Based on our findings, we present our plans for increasing the precision of our $\alpha$ measurement in the new apparatus to the level of one part in ten billion. We also observed that the interferometer signal is sensitive to the condensate critical temperature, and we propose BEC interferometry as a tool for studying phase transitions. In addition, we present a novel vapor cell with a short and a long path through the vapor, with independently adjustable optical densities. This single cell can be used for frequency stabilization on the two cooling transitions in Yb, which are separated by two orders of magnitude in strength. [Preview Abstract] |
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D1.00069: A Robust Ramsey Interferometer for Atomic Timekeeping in Dynamic Environments Krish Kotru, Justin Brown, David Butts, Jennifer Choy, Marissa Galfond, David M. Johnson, Joseph Kinast, Brian Timmons, Richard Stoner We present a laser-based approach to atomic timekeeping, in which atomic phase information is extracted using modified Raman pulses in a Ramsey sequence. We overcome systematic effects associated with differential AC Stark shifts and variations in laser beam intensity by employing atom optics derived from Raman adiabatic rapid passage (ARP). This technique drives coherent transfer between two hyperfine ground states by sweeping the frequency difference of two optical fields and maintaining a large single-photon detuning. Compared to a Raman-pulse Ramsey interferometer, we show a $\sim$100x reduction in sensitivity to differential AC Stark shifts. We also demonstrate that ARP preserves fringe contrast in Ramsey interferometers for cloud displacements reaching the 1/e$^2$ intensity radius of the laser beam. Deviations of the phase in response to changes in duration, rate, and range of the ARP frequency sweep are bounded to $<$7 mrad, implying a per-shot fractional frequency stability of 1e$^{-11}$ for an interrogation time of 10 ms. These characteristics are expected to improve the robustness of clock interferometers operating in dynamic environments. Copyright {\copyright} 2014 by The Charles Stark Draper Laboratory, Inc. All rights reserved. [Preview Abstract] |
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D1.00070: Magnetic Waveguide for Atom Interferometry and Inertial Navigation Applications Robert Horne, Charles Sackett Atom interferometry using Bose-Einstein condensates has potential applications in inertial navigation [1,2]. We present recent work on the development of a new magnetic waveguide specifically designed for these inertial navigation measurements. The waveguide is implemented using a modified Time Orbiting Potential (TOP) configuration that will allow support against gravity and provide a cylindrically symmetric, harmonic trapping potential for our $^{87}$Rb condensate. Based on simulations, the trap will be continuously adjustable, providing trapping frequencies in the horizontal plane from 1 Hz to 100 Hz. This will allow the implementation of a scalable gyroscope and an accelerometer using the same device. Additionally, the trap is continuously deformable from a harmonic potential to a ring trap. Trap characterization and additional measurement results will also be presented.\\[4pt] [1] K. J. Hughes, J. H. T. Burke, and C. A. Sackett, Phys. Rev. Lett. 102, 150403 (2009)\\[0pt] [2] J. H. T. Burke and C. A. Sackett, Phys. Rev. A 80, 061603(R) (2009) [Preview Abstract] |
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D1.00071: AMO-BASED SESNSORS: FUNDAMENTAL PHYSICS AND APPLICATIONS |
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D1.00072: A Nuclear-Electronic Spin Gyro-Comagnetometer Geoffrey Renon, Nassim Zahzam, Yannick Bidel, Alexandre Bresson, Pierre-Jean Nacher We have started a project aiming to fully characterize a new generation of atomic gyroscope very promising for applications requiring miniature sensors with high performances. Our experiment is based on the detection of a nuclear spin orientation with an alkali magnetometer [1]. The key element of the device is a spherical gas cell filled with an alkali gas (Rb) with an electronic spin and a noble gas ($^{129}$Xe) with a nuclear spin and heated at about 110 $^{\circ}$C and shielded from parasite magnetic fields. The first step of our project was the conception of the atomic spin gyroscope. The second step was the realization and the validation of the filling system. The gas mixture filled into the spherical cells was checked by the study of the collisional broadening and frequency shift of the D1 lines of the Rb. We are currently analyzing the $^{129}$Xe polarization by NMR and measuring the spin-exchange and relaxation parameters to estimate the future gyroscope performances. In parallel, the realization and of a first prototype of atomic spin gyroscope is in progress.\\[4pt] [1] T.W. Kornack, et al., ``Nuclear Spin Gyroscope Based on an Atomic Comagnetometer,'' PRL, vol. 95, 230801, 2005. [Preview Abstract] |
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D1.00073: An all-optical vector atomic magnetometer for fundamental physics applications David Wurm, Ignacio Mateos, Elena Zhivun, Brian Patton, Peter Fierlinger, Douglas Beck, Dmitry Budker We have developed a laboratory prototype of a compact all-optical vector magnetometer. Due to their high precision and absolute accuracy, atomic magnetometers are crucial sensors in fundamental physics experiments which require extremely stable magnetic fields (e.g., neutron EDM searches). This all-optical sensor will allow high-resolution measurements of the magnitude and direction of a magnetic field without perturbing the magnetic environment. Moreover, its absolute accuracy makes it calibration-free, an advantage in space applications (e.g., space-based gravitational-wave detection). Magnetometry in precision experiments or space applications also demands long-term stability and well-understood noise characteristics at frequencies below $10^{-4}$ Hz. We have characterized the low-frequency noise floor of this sensor and will discuss methods to improve its long-time performance. [Preview Abstract] |
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D1.00074: Search for a long-range, monopole-dipole (spin-mass) coupling of the proton Jordan Dudley, Julian Valdez, Claudio Sanchez, Dominic Fuentes, Derek Jackson Kimball We discuss progress in our search for a hypothetical long-range coupling between rubidium (Rb) nuclear spins and the mass of the Earth [D. F. Jackson Kimball et al., Annalen der Physik 525(7), 514-528 (2013)]. The experiment consists of simultaneous measurement of the spin precession frequencies of overlapping ensembles of Rb-85 and Rb-87 atoms contained within an evacuated, antirelaxation-coated vapor cell. Because of the nuclear structure of Rb-85 and Rb-87, the experiment is particularly sensitive to anomalous spin-dependent interactions of the proton. We have studied a number of important systematic effects related to vector and tensor light shifts, the nonlinear Zeeman effect, the ac Zeeman effect, collisions, and the rotation of the Earth. We anticipate that our experiment can improve sensitivity to anomalous long-range spin-mass couplings of the proton compared to previous experiments by an order of magnitude. [Preview Abstract] |
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D1.00075: Towards a Noble Gas Oscillator Anna Korver, Thad Walker Noble gas NMR detected by alkali co-magnetometers has the potential for measurement of precession frequencies at the pHz level. This is done by eliminating the dominant known sources of systematic errors: alkali frequency shifts and quadrupole shifts. We present results of successful synchronous pumping of noble gas nuclei and measurements of alkali co-magnetometer sensitivity levels that project a 131-Xe noise level of 100 $\mathrm{nHz}/\sqrt{\mathrm{Hz}}$. Future dual noble-gas co-magnetometry promises to improve the noise level by a factor of 10 or more. This research is supported by the NSF and Northrop-Grumman Corp. [Preview Abstract] |
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D1.00076: Short range force measurements with optically trapped and cooled micro-spheres David Atherton, Gambhir Ranjit, Jordan Stutz, Mark Cunningham, David Karr, Andrew Geraci In ultra-high vacuum, optically-trapped and cooled dielectric microspheres show great promise as force sensors--the environmental decoupling of their center-of-mass motion enables sub-attonewton sensitivity. Hence, they can be used to investigate Casimir forces or for testing non-Newtonian gravity. We are developing an apparatus to trap and cool silica spheres in a combined optical dipole-cavity trap. We describe our experimental results on optical trapping and cooling and our progress towards demonstrating the sensitivity of the technique. Ultimately, with a sphere trapped in an anti-node close to an end-mirror of the cavity, Casimir forces due to the end-mirror will be measured as a frequency shift of the oscillator. These measurements of the Casimir force will be in a previously unexplored regime between the Force Proximity Approximation and the Casimir-Polder approximation. Discrepancies between the strength of gravity and other Standard Models forces suggest corrections to Newtonian gravity at the sub-millimeter length scale. Non-Newtonian gravity-like forces will be tested by monitoring the displacement of the sphere as a mass is brought behind the cavity mirror. [Preview Abstract] |
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D1.00077: Compact Atomic Magnetometer for Global Navigation (NAV-CAM) Michael Bulatowicz, Michael Larsen Northrop Grumman Navigation Systems Division is developing an atom-based magnetometer technology that has the potential for providing a global position reference independent of GPS. The NAV-CAM sensor is a direct outgrowth of the Nuclear Magnetic Resonance Gyro under development by the same technical team. It will be the only known magnetic field sensor capable of providing all 3 axes of magnetic vector direction and magnitude simultaneously with a whole-field scalar measurement, all within a single multi-axis sensing element measuring 4mm cube or smaller, essentially eliminating many of the problems encountered when using physically separate sensors or sensing elements. According to information presented by Ariyur et al at the 2010 American Control Conference [1], the anticipated accuracy of 10 pico-Tesla (pT) and precision of \textless 0.5 pT of the NAV-CAM sensor will enable magnetic determination of position with 20 meter accuracy and 1 meter resolution. [Preview Abstract] |
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D1.00078: Fetal Magnetocardiography with an Atomic Magnetometer Array Ibrahim Sulai, Zack DeLand, Colin Wahl, Ronald Wakai, Thad Walker Fetal magnetocardiography (fMCG) is a powerful technique for analyzing the heartbeat patterns of $\textit{in utero}$ fetuses. We present results from our array of four Spin-Exchange Relaxation-Free (SERF) rubidium-87 atomic magnetometers which has been used to detect and create these magnetocardiograms. We have demonstrated a magnetic noise sensitivity of $<10 \mathrm{fT}/\sqrt{\mathrm{Hz}}$, limited by the Johnson noise of the magnetically-shielded room. We discuss new design features and experimental practices that have increased our sensitivity and allowed us to successfully measure an fMCG at a gestational age of only 21 weeks. We hope to eventually apply these techniques to the detection and diagnosis of heartbeat arrhythmias, which, if detected early enough, can be treated $\textit{in utero}$. This work is supported by the National Institutes of Health. [Preview Abstract] |
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D1.00079: Quantum-Assisted Electrometry using Electromagnetically Induced Transparency with Rydberg Atoms in a Vapor Cell Haoquan Fan, Santosh Kumar, Renate Dashner, Harald K\"{u}bler, Jon Sedlacek, James Shaffer We demonstrate a new type of atomic standard for microwave electric fields using Rydberg atoms in a vapor cell. We have used a bright resonance prepared within an electromagnetically induced transparency window in a Rydberg atom to achieve an electrometer with a sensitivity of 30 $\mu$V cm$^{-1}$ $\sqrt{Hz}$$^{-1}$. In addition, we have demonstrated vector electrometry at a resolution of 0.5$^{o}$ with similar sensitivity. Recently, we have also shown this scheme can achieve sub-wavelength spatial resolution $\lambda$/1933. Our experimental results agree very well with the finite difference time domain calculations. We present a summary of our experiments on atom-based electrometry to date. [Preview Abstract] |
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D1.00080: Green astro-comb for exoplanet searches: improved hardware and operation Nicholas Langellier, Nabila Tanjeem, Alexander Glenday, Chih-Hao Li, Gabor Furesz, David Phillips, Guoqing Chang, Hung-Wen Chen, Jinkang Lim, Franz Kaertner, Andrew Szentgyorgyi, Ronald Walsworth Searches for extrasolar planets using the precision stellar radial velocity (RV) measurement technique are approaching Earth-like planet sensitivity. Astro-combs, which consist of a laser frequency comb, coherent wavelength shifting mechanism (such as a doubling crystal and photonic crystal fiber), and a mode-filtering Fabry-Perot cavity (FPC), provide a promising route to increased accuracy and long-term stability on the astrophysical spectrograph calibration. We present the design of a green astro-comb from an octave spanning Ti:Sapphire laser, spectrally broadened by custom tapered PCF to the visible band via fiber-optic Cherenkov radiation for frequency shifting, and filtered by a broadband FPC, constructed by a pair of complementary chirped mirrors. Performance of this astro-comb and enhancements for improved operation at the HARPS-N spectrograph will be presented. [Preview Abstract] |
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D1.00081: A cryogenic quantum gas scanning magnetic microscope Richard Turner, Matthew Naides, Ruby Lai, Jack DiSciacca, Benjamin Lev Improved measurements of strongly correlated and topologically non-trivial systems open the path to a better fundamental understanding of these materials as well as the possibility for predictive design of new materials. We are working to demonstrate atom chip trapping of quantum gases to enable single-shot, large area imaging of electronic transport through these materials via detection of magnetic flux at the $10^-7$ flux quantum level and below. Using the exquisite sensitivity of ultracold atoms in the form of either an atomic clock or Bose-Einstein condensate, the cryogenic atom chip technology we have recently demonstrated [1] will provide a magnetic flux detection capability that surpasses other techniques while allowing sample temperatures spanning $<10$ K to room temperature. We will report on experimental progress toward developing this novel quantum gas scanning magnetic microscope and describe our recent proposal to image topologically protected transport through a non-ideal topological insulator in a relatively model-independent fashion.\\[4pt] [1] M. A. Naides, R. W. Turner, R. A. Lai, J. M. DiSciacca, and B. L. Lev, Trapping ultracold gases near cryogenic materials with rapid reconfigurability, Appl. Phys. Lett. 103, 251112 (2013) (2013). [Preview Abstract] |
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D1.00082: A Wide-Field NV Diamond Magnetic Imager for Highly Parallel Detection of Rare Biological Targets David Glenn, Kyungheon Lee, Hakho Lee, Ronald Walsworth We have developed a wide-field magnetic imaging device based on Nitrogen Vacancy centers in diamond, optimized for the detection of rare, immunomagnetically labeled biological targets such as circulating tumor cells. The new imager allows simultaneous magnetic imaging over a $\sim$ 1 mm$^2$ field of view, approximately two orders of magnitude larger than previous implementations. We describe experiments to detect cancer cells tagged with superparamagnetic nanoparticles, including validation studies for a cell detection assay and technical considerations associated magnetic imaging over very wide fields of view. [Preview Abstract] |
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D1.00083: Nanoscale MRI with Nitrogen-Vacancy centers in diamond Igor Lovchinsky, Alex Sushkov, Eric Bersin, Nicholas Chisholm, Hongkun Park, Mikhail Lukin In the last several decades Magnetic resonance imaging (MRI) has emerged as a powerful tool in science and technology. Conventional MRI technology, however, relies on measuring magnetic fields from a large (macroscopic) number of molecules, for example tissues in specific areas of the brain. ~Extending these techniques to the nanoscale could enable revolutionary advances in the physical, biological and medical sciences. Here we report on recent progress in using Nitrogen-Vacancy (NV) centers in diamond to detect small numbers of nuclear spins in biological molecules. [Preview Abstract] |
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D1.00084: COHERENT AND ULTRACOLD SPINS |
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D1.00085: Use of the ground state of a BEC in a double-well trap in quantum metrology Han Chen, Juha Javanainen The ground state of a Bose-Einstein condensate with attractive atom-atom interactions in a double-well trap is close to the NOON state. We discuss Heisenberg-limited atom interferometry starting with this state. We identify the dimensionless parameter governing the quality of the ground state for the purposes of quantum metrology. The ground state and the lowest-energy excited state become degenerate in the limit of strong atom-atom interactions, and thermal preparation of a state useful for precision measurements does not appear feasible. [Preview Abstract] |
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D1.00086: Optical response of a dense gas of moving atoms Yi Li, Sungmi Yoo, Juha Javanainen At high density, dipole-dipole interactions between the atoms may have a major impact on light propagation in a dense gas. We have developed a classical-electrodynamics simulation to study the cooperative response of a near-resonant gas to light. We take into account the motion of the radiators using classical trajectories, including collisions with the walls of the container and atom-atom collisions, and describe the transition from homogeneously broadening to inhomogeneously broadened phenomenology. [Preview Abstract] |
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D1.00087: Towards a Negative Refractive Index in an Atomic System Zach Simmons, Nick Brewer, Deniz Yavuz The goal of our experiments is to obtain a negative index of refraction in the optical region of the spectrum using an atomic system. The concept of negative refraction, which was first predicted by Veselago more than four decades ago, has recently emerged as a very exciting field of science. Negative index materials exhibit many seemingly strange properties such as electromagnetic vectors forming a left-handed triad. A key potential application for these materials was discovered in 2000 when Pendry predicted that a slab with a negative refractive index can image objects with a resolution far better than the diffraction limit. Thus far, research in negative index materials has primarily focused on meta-materials. The fixed response and often large absorption of these engineered materials motivates our efforts to work in an atomic system. An atomic media offers the potential to be actively modified, for example by changing laser parameters, and can be tuned to cancel absorption. A doped crystal allows for high atomic densities compared to other atomic systems. So far we have identified a transition in such a material, Eu:YSO, as a candidate for these experiments and are performing spectroscopy on this material. [Preview Abstract] |
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D1.00088: Interactions of cold rubidium atoms with a magnetic reflector Timothy Roach, Katelyn Candee We report on experiments on the scattering of cold Rb atoms from a sub-micron patterned permanent magnet made from a Zip disk. The atomic source is a magneto-optic trap. The locally strong, periodic magnetic field of the disk should reflect and diffract the atomic waves, provided the atoms in weak-seeking states adiabatically follow the field. Non-uniformity of the magnetic pattern and of the physical surface result in diffuse scattering and loss to state-changing transitions. We present results from the study of several controllable factors, including the initial atomic cloud temperature and size, and the strength and direction of a weak uniform magnetic field for preserving orientation. [Preview Abstract] |
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D1.00089: Spin Control on an Atom Chip Paul Kunz, David Meyer, Patricia Lee, Qudsia Quraishi Spin control of cold atoms is a rich area of research that continues to reveal insights into fundamental atomic and condensed matter physics while simultaneously offering promise for many devices and applications. Microfabricated atom chips are a convenient platform for investigating cold atoms as they provide magnetic trap and waveguide potentials for the atoms. We are developing a rubidium atom chip experiment, and have successfully trapped cold atoms on our chip. We are presently optimizing the system to achieve Bose Einstein condensation. We report on the status of our atom chip experiment, and our progress towards atomic spin control and coherence measurements. [Preview Abstract] |
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D1.00090: ABSTRACT WITHDRAWN |
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D1.00091: Exploring Entangled Two-Photon Absorption in Molecules John Caraher Goodson and colleagues have reported anomalously large cross-sections (of order $\sigma=10^{-17}$ cm$^2$) for the two-photon absorption of entangled photons in a number of molecules [1-3]. This poster reports on attempts to replicate and expand upon their results for one of these, zinc tetraphenylporphyrin (Zn TPP) in chloroform solution. It will also discuss the interpretation of the Goodson group's experimental data, particularly their results regarding entanglement area and entanglement time (the spatial and temporal widths of the fourth-order coherence functions, respectively)[4]. Results of direct measurement of entanglement time (via a Hong-Ou-Mandel interferometer) for a laser and optical system essentially identical to the one used in Goodson's work will be presented and compared with their reported values. \\[4pt] [1] D.-I. Lee and T. Goodson, III, J. Phys. Chem. B 110, 25582 (2006)\\[0pt] [2] M. R. Harpham, O. Suzer, C.-Q. Ma, P. Bauerle, and T. Goodson, III, J. Am. Chem. Soc., 131, 973 (2009)\\[0pt] [3] L. Upton, M. Harpham, O. Suzer, M. Richter, S. Mukamel, and T. Goodson, III, J. Phys. Chem. Lett. 4, 2046 (2013)\\[0pt] [4] B.E.A. Saleh, B.?M. Jost, H.-B. Fei, and M.C. Teich, Phys. Rev. Lett. 80, 3483 (1998) [Preview Abstract] |
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D1.00092: Spin Squeezing and Superradiance with a Collective Cavity QED System Joshua Weiner, Kevin Cox, Matthew Norcia, Justin Bohnet, James Thompson We present experiments that utilize cavity-mediated interactions between an ensemble of $\sim 10^6$ $^{87}$Rb atoms to create conditional spin squeezing and steady state superradiance. In one set of experiments, we employ quantum non-demolition measurements to obtain collective information about the pseudo-spin projection $J_z$ of the atoms and generate an improvement of 10.2(6) dB in quantum phase estimation relative to the standard quantum limit for a coherent spin state. A method for reducing the effects of microwave rotation errors on the observed spin noise reduction through controlled dephasing with a far off-resonant laser beam is also discussed. In separate experiments, we establish steady-state superradiance (or bad-cavity lasing) using a Raman transition between hyperfine ground states of rubidium. We present studies of active and passive sensing of external fields with a superradiant laser, amplitude stability, and phase synchronization between two spatially distinct ensembles emitting into a single optical cavity. These techniques could enhance future precision measurements in optical atomic clocks, atom interferometry, and long-baseline interferometry. [Preview Abstract] |
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D1.00093: Coherent manipulation by adiabatic passage of interacting Rydberg atoms inside a cavity Santosh Kumar, Charles Ewel, Jonathon Sedlacek, James Shaffer We investigate the coherent manipulation of interacting Rydberg atoms placed inside a cavity by using stimulated Raman adiabatic passage (STIRAP). In this approach, we consider a five-level double-ladder scheme with one common Rydberg level for N interacting atoms. One side of the ladder excites the atoms into the Rydberg level using counter-intuitive STIRAP pulses, while the other side of the ladder couples the atom to a cavity field. Due to the strong interaction between the atoms in the Rydberg level, the Rydberg blockade mechanism plays an important role in the manipulation of the atoms. We use numerical simulation to show that how one can generate non-classical states of light with this system. We consider how the decay mechanisms affect this interacting many-body system. [Preview Abstract] |
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D1.00094: A controlled-phase gate for matterwave interferometry Aaron Hankin, Yuan-Yu Jau, Grant Biedermann We are implementing a controlled-phase gate based on singly trapped neutral atoms whose coupling is mediated by the dipole-dipole interaction of Rydberg states. An off-resonant laser field dresses ground state cesium atoms in a manner conditional on the Rydberg blockade mechanism [1,2], providing the required entangling interaction. We will present our progress [3] and its connection to single-atom matterwave interferometry [4] with entangled atoms. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. \\[4pt] [1] S. Rolston, et al. Phys. Rev. A, 82, 033412 (2010)\\[0pt] [2] T. Keating, et al. Phys. Rev. A, 87, 052314 (2013)\\[0pt] [3] A. Hankin, et al. arXiv:1401.2191\\[0pt] [4] L. P. Parazzoli, et al. Phys. Rev. Lett., 109, 230401 (2012) [Preview Abstract] |
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D1.00095: Nondestructive measurement of an ultracold lattice gas Yogesh Patil, Harry Cheung, Srivatsan Chakram, Yariv Yanay, Erich Mueller, Mukund Vengalattore We realize a continuous measurement of a lattice gas of bosons via two photon fluorescence imaging. We characterize the effect of this measurement on the ultracold gas for various parameters of lattice depth, fluorescence acquisition rate and image resolution. Through sideband spectroscopy, we also quantify the heating induced on the atomic gas due to the imaging sequence. In addition to enabling the local measurements of transport and non-equilibrium dynamics of the lattice gas, our work also paves the way towards the use of continuous quantum measurements for the deterministic control of interacting many-body systems. \\[4pt] This work is supported by the ARO MURI on non-equilibrium dynamics. [Preview Abstract] |
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D1.00096: Numerical studies of localization of atomic excitation in systems with hyperfine structure Jungu Choi, Daniel Elliott We numerically study coherent population trapping (CPT) within a system such as Rubidium 87 that has multiple Zeeman sub-levels. Due to the multiplicity of hyperfine levels, the system forms a number of superposition states known as dark states, where the resonant laser interaction is suppressed by coherence coupling. The population ratio of the ground components of each dark state is dictated by the ratio of Rabi frequencies of the coupling and probe beams, which of course varies among the hyperfine components of the ground state. We have applied this CPT model to the case of an intense standing wave coupling laser and a uniform probe laser to observe atomic localization. Specifically, we examine the conditions that lead to the greatest degree of localization near the nodes of the coupling beam. We conclude that a long interaction time, as long as a microsecond, is essential to the formation of highly localized states. [Preview Abstract] |
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D1.00097: Investigation of quantum impedance matching in a cavity based quantum memory Zakary Burkley, Bertus Jordaan, Carl Cheung, Christian Noelleke, Connor Kupchak, Eden Figueroa Atomic ensembles are among the most promising candidates for the implementation of photonic quantum memories. A widely used technique to coherently store and retrieve photonic states from these systems is Electromagnetically Induced Transparency. Coupling the atoms to an optical cavity increases the light-matter interaction and results in high storage and retrieval efficiencies. Ultimately, the efficiency is limited by non-optimal impedance matching that results in partial reflection of the photon to be stored off the incoupling mirror. The reflection can be decreased by using control light of a certain temporal shape that causes the transmitted light to destructively interfere with the reflected light. We present an extensive study of impedance matching in a magneto-optical trap coupled to an optical cavity. We discuss the impact of our results towards real-world quantum networks, and how our system can be exploited to realize efficient photonic quantum gates. [Preview Abstract] |
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D1.00098: Polarization dependence of lineshapes in modulation transfer spectroscopy for 87Rb Atoms Heung-Ryoul Noh, Sang Eon Park We present the polarization dependence of the lineshapes in modulation transfer spectroscopy for the transitions from the lower ground state (Fg $=$ 1) of 87Rb atoms. We measured the spectra for the two polarization configurations: The carrier and probe beams were linearly polarized in parallel or perpendicular directions. The measured spectra were compared with the calculated results obtained by solving the density-matrix equation. We found that the spectra were strongly dependent on the polarization configurations. In particular, the signal for parallel polarization configuration was generated via an incoherent process mediated by spontaneous emission. [Preview Abstract] |
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D1.00099: Background Noise Analysis in a Few-Photon-Level Qubit Memory Thomas Mittiga, Connor Kupchak, Bertus Jordaan, Mehdi Namazi, Christian Nolleke, Eden Figeroa We have developed an Electromagnetically Induced Transparency based polarization qubit memory. The device is composed of a dual-rail probe field polarization setup colinear with an intense control field to store and retrieve any arbitrary polarization state by addressing a $\Lambda$ -type energy level scheme in a $^{87}$Rb vapor cell. To achieve a signal-to-background ratio at the few photon level sufficient for polarization tomography of the retrieved state, the intense control field is filtered out through an etalon filtrating system. We have developed an analytical model predicting the influence of the signal-to-background ratio on the fidelities and compared it to experimental data. Experimentally measured global fidelities have been found to follow closely the theoretical prediction as signal-to-background decreases. These results suggest the plausibility of employing room temperature memories to store photonic qubits at the single photon level and for future applications in long distance quantum communication schemes. [Preview Abstract] |
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D1.00100: Nonequilibrium States of a Quenched Bose Gas Hong Ling, Ben Kain Yin and Radzihovsky [Phys. Rev. A 88, 063611(2014)] recently developed a self-consistent extension of a Bogoliubov theory, in which the condensate number density, n$_{\mathrm{c}}$, is treated as a mean field that changes with time in order to analyze a JILA experiment by Makotyn et al. [Nature Physics doi:10.1038/nphys2850 (2014)] on a $^{85}$Rb Bose gas following a deep quench to a large scattering length. We apply this theory to construct a set of closed equations that highlight the role of dn$_{\mathrm{c}}$/dt, which is to induce an effective interaction between quasiparticles. We show analytically that such a system supports a steady state characterized by a constant condensate density and a steady but periodically changing momentum distribution, whose time average is described exactly by the generalized Gibbs ensemble. We discuss how the dn$_{\mathrm{c}}$/dt-induced effective interaction, which cannot be ignored on the grounds of the adiabatic approximation for modes near the gapless Goldstone mode, can affect experimentally measurable quantities such as Tan's contact. [Preview Abstract] |
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D1.00101: EIT-based quantum memory Gleb Romanov, Irina Novikova Efficient and long-living quantum memory is an important component of quantum repeaters. Quantum memory can be based on the effect of Electromagnetically Induced Transparency (EIT), which is an effect where one electromagnetic field (control) creates a window of transparency in a resonant atomic media for another electromagnetic field (probe). By adjusting the control field, one can control the dispersion seen by the probe field. This allows for observation of stored light by mapping the probe field onto the long-lived atomic coherence. In this report I will describe our progress towards improving the efficiency and storage time for the EIT-based quantum memory. [Preview Abstract] |
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D1.00102: Spatial correlation of quantum noise in a laser beam interacting with atomic ensembles Mi Zhang, Irina Novikova, Eugeniy Mikhailov We generated quantum squeezed states of light (with noise levels below the standard quantum limit or shot noise) utilizing the polarization self-rotation effect in a hot Rb vapor. We measured noise in the squeezed quadrature and the amplitude quadrature of a spatially-masked laser beam after its interaction with the Rb atomic vapor. We observed that the detected noise level was largely affected by the symmetry of the applied mask, rather than solely by the total power masked/removed from the beam. We also studied the dependence of the noise level on the Rb vapor density, and observed uncorrelated distribution of noise between different parts of the beam, which followed the power law dependence. Results of our studies are of interest for quantum metrology, spectroscopy, and quantum memory applications. [Preview Abstract] |
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D1.00103: Collective emission and collective quantum jumps of Rydberg atoms Lyndon Cayayan, Jacob Pauley, James Clemens We investigate collective quantum jumps in a driven, damped system of Rydberg atoms with a long range interaction in their excited states. The damping may be independent spontaneous emission or collective spontaneous emission depending on the spatial arrangement of the atoms. We present the probe spectrum and photon statistics of the emitted light as a function of the number of atoms, the strength of the long range interaction, the spontaneous emission rate and the type of emission. We also present individual stochastic trajectories as the atoms make collective jumps between a low excitation state and a high excitation state. [Preview Abstract] |
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D1.00104: Scattering properties of strongly interacting Rydberg polaritons Soonwon Choi, Przemek Bienias, Ofer Firstenberg, Mohammad Maghrebi, Mikhail Lukin, Alexey Gorshkov, Michael Gullans, Hanspeter Buchler The combination of Electromagnetically Induced Transparency(EIT) and strong Rydberg-Rydberg interaction can lead to a system of interacting polaritons [1,2]. In this poster, we present a theoretical analysis of two-polariton dynamics in Rydberg EIT medium [3]. We show that the effective polariton-polariton interaction is tunable to both attraction and repulsion and investigate its scattering properties. In the regime of attraction, we identify the formation of multiple two-polariton bound states and compute their dispersions. Finally, we discuss the implications of our results to the ongoing experiments and to the effective many body theory for strongly interacting Rydberg polaritons.\\[4pt] [1] T. Peyronel, and et al, Nature 488, 57 (2012)\\[0pt] [2] O. Firstenberg, and et al, Nature 502, 71 (2013)\\[0pt] [3] P. Bienias, and et al, (in preparation) [Preview Abstract] |
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D1.00105: Apparatus for generating highly squeezed collective atomic spin states Nils Johan Engelsen, Rajiv Krishnakumar, Onur Hosten, Mark Kasevich Production of spin-squeezed atomic ensembles could greatly enhance the performance of existing atom-based sensors by overcoming the atomic shot-noise inherent in sensors with uncorrelated atoms. We pursue a measurement based method for spin squeezing inside of a high-finesse cavity, potentially enabling spin-squeezing at 20 dB in variance, compatible with releasing the generated states into free space. We use a dual-wavelength cavity, resonant at both 780 nm and 1560 nm, with a finesse of 10$^{5}$. Up to 10$^{5}$ Rubidium atoms can be trapped at the anti-nodes of the 1560 nm mode, and probed by the 780 nm mode. The commensurate wavelength relationship allows identical coupling of the probe light to all atoms, minimizing decoherence issues associated with inhomogeneous coupling Thus far we have engineered a homodyne detection system that has an empty cavity technical read-out noise level of 10Hz in 200$\mu $s measurement intervals, corresponding to the resonance shift induced by an individual atom at a probe detuning of $\sim$ 1GHz. This technical noise level is so low that it has no significant effect in the preparation of the anticipated squeezed states. At the time of writing, we have demonstrated back-to-back measurements with 20x10$^{3}$ atoms, with 0.02 photons scattered per atom in a measurement interval of 200$\mu$s, that exhibit read-out noise levels compatible with 10-17dB of squeezing. [Preview Abstract] |
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D1.00106: Probing quantum dynamics of strongly interacting spin ensembles Georg Kucsko, Peter Maurer, Norman Yao, Michael Knap, Sarang Gopalakrishnan, Mikhail Lukin Ensembles of strongly interacting spins offer an attractive platform for the study of novel many-body states in quantum dynamics. This work focuses on recent progress towards understanding the spin dynamics within a diamond sample of very high nitrogen vacancy (NV) concentration ($\sim$80 ppm). Due to the small distance between neighboring NVs, their interactions dominate over decoherence. Experimental observations of quantum spin dynamics in such a system as well as probing of localization of spin excitations will be discussed. [Preview Abstract] |
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D1.00107: PHOTON INTERACTIONS WITH ATOMS, IONS AND MOLECULES |
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D1.00108: Field ionization and photoionization of CH$_3$I perturbed by diatomic molecules: Electron scattering in H$_2$, HD, D$_2$, O$_2$ and CO Cherice Evans, Kamil Krynski, Zachary Streeter, Ollieanna Burke, Gary L. Findley Photoionization and field ionization studies of CH$_3$I doped into the diatomics H$_2$, HD, D$_2$, O$_2$ and CO (up to a density of $\rho = 1.0 \times 10^{21}$ cm$^{-3}$) are presented. These data are used to extract the zero-kinetic-energy electron scattering length of each diatomic molecule from the density-dependent shift of the CH$_3$I ionization energy. Scattering lengths obtained from fits of the photoionization spectra are compared to those determined from field ionization measurements. [Preview Abstract] |
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D1.00109: State-selective generation of molecular ions via Rydberg states David Grimes, Yan Zhou, Timothy Barnum, Stephen Coy, Jeffrey Kay, Robert Field Autoionizing Rydberg states of molecules in the range n=30-50 have the potential to enable the production of single quantum state selected ensembles of molecular ions, which have uses from spectroscopy to high precision measurements of fundamental constants [1]. Multichannel Quantum Defect Theory (MQDT) fully describes the Rydberg states of molecules and the dynamics of autoionization. We have used our full MQDT description of CaF [2] to determine optimal autoionizing resonances for producing a variety of selected rotation-vibration states of the ion. Progress towards experimental demonstrations in BaF will also be discussed. \\[4pt] [1] H. Loh, J. Wang, M. Grau, T. Yahn, R. Field, C. Greene, and E. Cornell, J. Chem. Phys. 135, 154308 (2011). \\[0pt] [2] J. Kay, S. Coy, B. Wong, C. Jungen, and R. Field, J. Chem. Phys. 134, 114313, (2011). [Preview Abstract] |
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D1.00110: Photoionization of Nitromethane at 355nm and 266nm Denhi Mart\'Inez, Francisco Betancourt, Juan Carlos Poveda, Alfonso Guerrero, Carmen Cisneros, Ignacio \'Alvarez Nitromethane is one of the high-yield clean liquid fuels, i.e. , thanks to the oxygen contained in nitromethane, much less atmospheric oxygen is burned compared to hydrocarbons such as gasoline, making the nitromethane an important prototypical energetic material, the understanding of its chemistry is relevant in other fields such as atmospheric chemistry or biochemistry. In this work we present the study of photoionization dynamics by multiphoton absorption with 355nm and 266 nm wavelength photons, using time of flight spectrometry in reflectron mode (R-TOF). Some of the observed ion products appear for both wavelength and other only in one of them; both results were compared with preview observations and new ions were detected. [Preview Abstract] |
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D1.00111: Broadband Continuous-Wave Light Modulation at Molecular Frequencies Joshua Weber, David Gold, Deniz Yavuz We use continuous-wave (CW) stimulated Raman scattering inside a deuterium-filled, high-finesse cavity as a wavelength-independent molecular modulator. Intense CW laser beams drive a two-photon vibrational transition in deuterium and build up a coherence between molecular states. Any incident independent beam then mixes with this coherence and generates frequency-shifted sidebands in a single pass through the cavity. The frequency shift is approximately 89 THz, which corresponds to the Raman transition frequency. Our goal is to exploit this large modulation frequency and the broadband capabilities of the modulator to generate a CW spectrum spanning the full range of optical frequencies. [Preview Abstract] |
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D1.00112: Multi channel quantum defect theory calculations of the Rydberg spectra of HCO Nicolas Douguet, Ann Orel We present a first-principles theoretical study of the photoionization spectra of vibrationally autoionizing Rydberg states converging to excited states of HCO$^+$. The clamped-nuclei scattering matrix, quantum defects parameters and transition dipole moments are explicitly calculated using the complex variational Kohn technique. The multi-channel quantum defect theory and vibrational frame transformation are then used to calculate the absorption spectrum. The results are compared with experimental data on double-resonance spectroscopy of the high Rydberg states of formyl radical. [Preview Abstract] |
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D1.00113: Directing broadband THz using ionizing two-color laser pulses with tilted-intensity fronts Luke Johnson, Thomasc Antonsen, John Palastro, Ki-Yong Kim, Jared Wahlstrand The ionization of molecular nitrogen by an ultrashort pulse and its second harmonic results in a low frequency photocurrent that drives coherent, broadband THz radiation [1]. The emission angle of the THz is determined by an optical Cherenkov process [2]. To direct this emission, while maintaining the overall yield, we propose tilting the intensity front of the ionizing pulse. We will present simulations demonstrating the influence of the tilt angle on the THz energy, spectrum, and emission angle and compare this to experimentally observed asymmetries in THz radiation patterns.\\[4pt] [1] K. Y. Kim, Phys. Plasmas 16, 056706 (2009). \newline[2] L. A. Johnson, et al., Phys. Rev. A 88, 063804 (2013) [Preview Abstract] |
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D1.00114: Control of the Atomic Ionization with Short and Intense Chirped Laser Pulses Salima Hennani, Stephane Laulan, Samira Barmaki We investigate a two-photon ionization process in a real hydrogen atom by short and intense chirped laser pulses. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schr\"{o}dinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an accurate L2 discretization technique based on the expansion of the wave functions on B-spline functions. We show the efficiency of chirped laser pulses to control the ionization yield and the transfer of the population to the 2$p$ bound state involved in the ionization path. [Preview Abstract] |
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D1.00115: Direct observation of strong-field enhanced ionization in CO and N2 Wei Lai, Chunlei Guo Enhanced ionization (EI) of molecules has been predicted as a common process in molecular dissociative ionization in strong fields over two decades ago. However, direct evidence for EI has only been found in I2 and H2. In this work, we perform the first direct study of EI in CO and N2. In two sets of pump-probe experiments, one with 68-fs pulses and one with 45-fs pulses, we consistently observed a new dissociation channel in each of these two molecules following double ionization that has not been previously resolved. Interestingly, EI occurs only in the newly discovered channels with a lower kinetic energy release but, surprisingly, does not happen in the commonly-seen dissociation channels that were previously assigned undergoing EI. [Preview Abstract] |
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D1.00116: Phase-dependent ionization suppression in atoms and molecules David B. Foote, Jane Lee, Guan-Yeu Chen, Wendell T. Hill, III Evolving methods in ultrafast laser pulse shaping allow a more complete investigation into the role of both the carrier envelope phase (CEP) and chirp in quantum control experiments. Recent investigations suggest that phase is one of the key parameters in quantum control mechanisms. To reveal the nature of the role phase plays we have employed a phase-only spatial light modulator (SLM) to shape 800 nm, sub-60 fs transform-limited pulses into a pair of transform-limited pulses ($\sim$ 60 fs) where the relative phase and temporal separation can be adjusted independently. At a fixed temporal separation, approximately three times the pulse width, the ionization signal was measured as the phase was varied over 2$\pi +$. The ionization signals show a periodic dependence on the phase; at specific phase values the second pulse was rendered impotent, leading to an ionization suppression in both atomic and molecular systems. When the temporal separation was adjusted, a propensity for the relative phase between the two carriers to remain fixed was observed. This suggests that the phase difference could be responsible for ``trapping'' population in states inaccessible to ionization. These results and their implication will be presented in this poster. [Preview Abstract] |
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D1.00117: Multielectron effects in molecular dynamics driven by intense laser pulses Yuqing Xia, Felipe Cajiao- Velez, Agnieszka Jaron-Becker Using time-dependent density functional theory, we study multi-electron effects on high harmonic generation (HHG) and strong field ionization (SFI) from molecules. Both HHG and SFI although related to extreme distortion of an electron wave function in a system in the presence of a strong laser field, were so far successfully studied with theories based on 'single active electron' (SAE) approximation such as 'Strong Field Approximation'. We show several examples of novel resonant coupling, when the SAE description is not sufficient and analyze situations when it can be observed in experiment. [Preview Abstract] |
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D1.00118: Self-consistent method for extraction of attosecond photoabsorption streaking time delays Hongcheng Ni, Jing Su, Agnieszka Jaro\'n-Becker, Andreas Becker We propose a self-consistent method to account for the Coulomb-laser coupling effect and obtain intrinsic photoabsorption time delays measured by the attosecond streak camera technique. We illustrate this method for a one dimensional numerical model of the hydrogen atom. In our method, starting from a first guessed time delay, we iteratively obtain a streaking trace, fit the trace to the vector potential of the streaking pulse, and obtain a new time delay. The iteration procedure is repeated until the time delay converges. We demonstrate the convergence and robustness of the method. [Preview Abstract] |
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D1.00119: 3d photoionization of ions from the xenon isonuclear sequence S. Schippers, A. M\"{u}ller, A. Borovik Jr., J. Hellhund, K. Holste, D. Schury, S. Klumpp, K. Mertens, M. Martins, R. Flesch, G. Ulrich, E. R\"{u}hl, J. Lower, T. Jahnke, D. Metz, L. Ph. H. Schmidt, M. Sch\"{o}ffler, J. Williams, R. D\"{o}rner, J. Viefhaus, A. Dorn, A. Wolf, J. Ullrich, T. Buhr, S. Ricz The photon-ion merged-beams technique has been employed at the new \underline{P}hoton-\underline{I}on spectrometer at \underline{PE}TRA\,III (PIPE) for measuring multiple photoionization of Xe$^{q+}$ ($q$=1--5) ions. Total ionization cross sections have been obtained on an absolute scale for the dominant ionization reactions of the type $h\nu + \mathrm{Xe}^{q+} \to \mathrm{Xe}^{r+} + (q-r)e^-$ with product charge states $q+2\leq r \leq q+5$. Prominent ionization features have been observed in the photon-energy range 650--800 eV, which are associated with excitation or ionization of an inner-shell $3d$ electron. The well-known collapse of the $4f$ wave function causes dramatic changes in the spectra when going from low to high $q$. [Preview Abstract] |
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D1.00120: Morphology dependence of multi-photon ionization of bulk GaAs Evan Brunkow, Nathan Clayburn, Herman Batelaan, Timothy Gay Using a Ti:Saph femtosecond oscillator with average power between 100 and 200 mW and a 20 fs pulse width ($\sim$ 10 nJ/pulse), we previously found that we could excite electrons from bulk GaAs using multi-photon absorption [1]. Further investigation has shown that the number of electrons emitted per laser pulse depends on the part of the crystal from which the electrons are being emitted. Emission from bulk GaAs, edges of rectangular GaAs surfaces, and tips of GaAs shards appears to give significantly different quantum efficiency. In the bulk, we generally see very few electrons emitted, except from occasional ``hot'' spots where we see some emission ($\sim$ 10$^{2}$ Hz). These spots appear to be randomly spaced and we have been unable to discern their nature. On the edges of a crystal, we see an increase in electron counts and typically observe 10$^{3}$-10$^{5}$ Hz. When we make a crystal that has a sharp point on the tip, we have seen rates as high as 10$^{5}$-10$^{7}$ Hz. We will present systematic data related to emission from various GaAs targets, as well as the results of several investigations into the temporal characteristics of these pulses. \\[4pt] [1] E. Brunkow et al., Bull. Am. Phys. Soc. \textbf{58}, 38 (2013) [Preview Abstract] |
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D1.00121: ABSTRACT WITHDRAWN |
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D1.00122: Rovibrationally-resolved photodissociation of NH and application to the solar UV opacity G. Shen, A. Kuri, J.M. Fontenla, P.C. Stancil, J.G. Wang Rovibrationally-resolved photodissociation cross sections of NH have been evaluated using a combination of ab initio and experimentally derived potential curves and dipole transition moments. Here we present results for the three electronic transitions: $2~^3\Sigma^- \leftarrow$ X$~^3\Sigma^-$, $2~^3\Pi \leftarrow$ X$~^3\Sigma^-$, A$~^3\Pi\leftarrow$ X$~^3\Sigma^-$. Partial cross sections for transitions from all 577 rovibrational levels obtained theoretically for the ground electronic state X$~^3\Sigma^-$, were computed for a wavelength range that extends from 500\AA\ to the dissociation threshold for each particular rovibrational level. Assuming a thermal Boltzmann distribution of the rovibrational levels in X$~^3\Sigma^-$, LTE cross sections are presented for gas temperatures between 500 and 10000~K. For applications to cold interstellar gas, cross sections for X$~^3\Sigma^-(v=0,J=0)$ to $2~^3\Sigma^-$ and $2~^3\Pi$ dominate, but for the high density and temperature conditions in stellar atmospheres, the LTE cross section to the A$~^3\Pi$ becomes competitive. Explicit application of the cross sections to the solar UV opacity will be presented. In particular, the NH photodissociation opacity is found to affect the non-LTE behavior of some species such as Cr I and V I. [Preview Abstract] |
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D1.00123: Dynamic of charge asymmetric dissociation in strong laser fields Wei Lai, Chunlei Guo We perform a comparison study on the dynamics of double-ionization induced charge asymmetric dissociation (CAD) in two isoelectronic diatomic molecules, CO and N$_2$. With ultrahigh temporal resolution time-of-flight measurements, CAD channel C$^{2+}$+O shows a clear intensity dependence for its kinetic energy release (KER). This is interesting because a neutral atom presents in the dissociation and thus, the channel should not gain a significant amount of Coulomb energy during the molecule dissociation. In comparison, the counterpart CAD channel N$^{2+}$+N has nearly a constant KER. Our studies show that the C$^{2+}$+O channel is predominantly produced through a sequential process whereas the N$^{2+}$+N channel involves a nonsequential transition. Their distinctly different dynamics are attributed to the different electronic configurations of the two isoelectronic molecules. [Preview Abstract] |
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D1.00124: Disintegration Symmetries of Non-Spherical Clusters in X Ray Laser Pulses Edward Ackad, Joseph Trost Clusters tend to form an icosahedral structure with most of the atoms on the surface of the cluster. When irradiated with an ultra-intense short X Ray pulse, such as pulses from the new X Ray free laser sources, the dynamics of the ions is driven by the internal nanoplasma, not the laser as in IR pulses. We report on our findings that the cluster disintegrates with the same symmetry as the initial structure, even if the cluster is highly non-spherical. Thus a measurement of the ion signal's anisotropy could be used to know the initial orientation of a non-spherical object such as a protein being imaged using single-shot diffraction imaging at an X Ray free-electron laser facility (LCLS). [Preview Abstract] |
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D1.00125: Profound role of inelastic electron collisions in endohedrals' photoabsorption Miron Amusia, Larissa Chernysheva, Eugene Drukarev We demonstrate that a photoelectron on its way out of an inner atom in an endohedral at reasonably high photon energy has an almost 100{\%} probability to collide inelastic with electrons of the fullerenes shell. As a result the one-electron photoionization cross-section tends to zero. All its total oscillator strength goes to ionization channels that include along with elimination of the electron from the inner atom, also elimination of one or several fullerenes electrons. As a result the photon absorption is followed by emission of additional electrons and carbon ions or atoms. With photon energy decrease this inner inelastic collision becomes gradually less and less important. We estimate the energy of disappearance of inner collisions and demonstrate that for Xe@C60 ionization the C60 cannot be substituted by a static pseudo-potential already at photon energies of about 100 eV. At this energy the inelastic collision of photoelectrons from 4d Xe with C60 contributes about 80{\%} of the total photoabsorption cross-section. This result explains why calculations that include automatically all two and multi-step processes give cross-sections that are by about an order of magnitude bigger than the experimentally measured one-channel cross-sections. [Preview Abstract] |
(Author Not Attending)
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D1.00126: Experimental Measurements of the Electron Affinity of Gallium and the Fine Structure of Ga$^{-}$ N.D. Gibson, C.W. Walter, C.T. Crocker, J.N. Yukich The electron affinity of gallium and the negative ion fine structure splittings of Ga$^{-}$ have been measured using tunable laser photodetachment threshold spectroscopy. The relative cross sections for neutral atom production were measured with a crossed laser-ion beam apparatus over the photon energy range 0.27 -- 0.41 eV. An $s$-wave threshold was observed due to the opening of the Ga$^{-}$ (4$p^{2} \quad^{3}P_{0})$ to Ga (4$p$ $^{2}P_{1/2})$ ground-state to ground-state transition, yielding a preliminary value for the Ga electron affinity. $s$-wave thresholds were also observed for detachment from the J $=$ 1 and J $=$ 2 excited levels of Ga$^{-}$, yielding preliminary values for the fine structure splittings. The present values are compared with previous experimental [1, 2] and theoretical results [3-5]. \\[4pt] [1] W. W. Williams \textit{et al}., J. Phys. B \textbf{31}, L341 (1998); \\[0pt] [2] T. Andersen \textit{et al.}, J. Phys. Chem. Ref. Data \textbf{28}, No. 6, 1511 (1999). \\[0pt] [3] D. Sundholm \textit{et al.}, J. Phys. B \textbf{32,} 5853 (1999).\\[0pt] [4] J. Li\textit{ et al.}, J. Phys. B \textbf{45} 16500 (2012).\\[0pt] [5] Z. Felfli, \textit{et al.}, J. Phys. B \textbf{45 }045201 (2012). [Preview Abstract] |
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D1.00127: Compression of Electron Pulses for Femtosecond Electron Diffraction Omid Zandi, Jie Yang, Martin Centurion Our goal is to improve the temporal resolution in electron diffraction experiments to 100 fs by compressing the electron pulses using a time-varying electric field. The compressed pulse can be used for a better understanding of the dynamics of molecules under study. A bunch of 3 million electrons is generated at a photocathode by femtosecond UV laser pulses and accelerated to 100 keV in a static electric field. Then, the longitudinal component of the electric field of a microwave cavity is employed to compress the bunch. The cavity's frequency and phase are accurately tuned in such a way that the electric field is parallel to the bunch motion at its arrival and antiparallel to it at its exit. Compression in the transverse directions is done by magnetic lenses. Simulations have been done to predict the bunch profile at different positions and times by General Particle Tracer code. A streak camera has been built to measure the duration of the pulses. It uses the electric field of a discharging parallel plate capacitor to rotate the bunch so that angular spreading of the bunch is proportional to its duration. The capacitor is discharged by a laser pulse incident on a photo switch. [Preview Abstract] |
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D1.00128: Confinement marries correlation to control time delays in valence-photoemissions of Ar taken hostage in C$_{60}$ Himadri Chakraborty, Gopal Dixit, Mohamed Madjet Effects of confinement and electron correlations on the relative time delay between the 3s and 3p photoemissions of Ar confined endohedrally in C$_{60}$ are investigated using the time dependent local density approximation [1] - a method that is also found to mostly agree with recent time delay measurements between the 3s and 3p subshells in atomic Ar [2]. The Leeuwen and Baerends exchange-correlation functional to produce accurate asymptotic behavior is employed to calculate the dynamical response of the system to the photon field. At energies in the neighborhood of 3p Cooper minimum, correlations with C$_{60}$ electrons are found to induce opposite temporal effects in the emission of Ar 3p hybridized symmetrically versus that of Ar 3p hybridized antisymmetrically with C$_{60}$ [2]. A recoil-type interaction model mediated by the confinement is found to best describe the phenomenon. We suggest that future experiments be performed on the time delay in Ar and Ar@C$_{60}$ over broader photon energy ranges including the 3p Cooper minimum to unravel new physics from confinement and correlations.\\[4pt] [1] M.E. Madjet, T. Renger, D.E. Hopper, M.A. McCune, H.S. Chakraborty, J.-M. Rost, and S.T. Manson, \textit{Phys. Rev. A} 81, 013202 (2010);\\[0pt] [2] G. Dixit, H.S. Chakraborty, and M.E. Madjet, \textit{Phys. Rev. Lett.} 111, 203003, (2013). [Preview Abstract] |
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D1.00129: Exploration of ultra-fast electron dynamics using time-dependent R-matrix theory Hugo van der Hart, Hector Rey, Ola Hassouneh, Andrew Brown When an atom is subjected to an intense laser field, the full atomic response can involve a collective response involving several electrons. This collective response will be affected by electron-electron repulsion, coupling the overall electron dynamics. In order to investigate this dynamics for a multi-electron system from first principles, we have developed time-dependent R-matrix theory. The theory applies the basic principles of R-matrix theory, in which all interactions between all electrons are taken into account close to the nucleus, but exchange interactions are neglected when one electron has become distanced from the parent atom. In this contribution, we will explain the basic principles of this theory and demonstrate its application to ultra-fast dynamics in C$^{\mathrm{+}}$, and harmonic generation in singly ionised noble-gas atoms. Both studies demonstrate that it is important to go beyond the single-active-electron approximation. [Preview Abstract] |
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D1.00130: Quantum-classical correspondences in time-dependent rotational revival spectra for asymmetric rotors in strong fields Josiah Cochran, Edward Hamilton Time-dependent rotational recurrence spectroscopy of asymmetric molecules reveals strong revival structures characteristic of a system in which quantum dynamics are strongly reflecting a small number of underlying classical trajectories. The classical rotor allowed to spin in the presence of a weak external field is chaotic in nature, filling all of phase space, but it can be pinned on its unstable axis and forced into a precessional motion that is confined phase space by a sufficiently strong electric field. Our area of interest is intermediate parameter choices between the free rotor and the pendular where closed periodic orbits are surrounded by chaotic ones. A study of this area of phase space will be performed by gradually turning off the field, and compared with statistical properties of the associated quantum system that are diagnostic of the onset of quantum chaos. [Preview Abstract] |
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D1.00131: Time-dependent local density approximation (TDLDA) studies of quantum phases and time delays in bound-continuum transitions of Kr Maia Magrakvelidze, Gopal Dixit, Mohamed Madjet, Himadri Chakraborty We calculate the phases of photoionization and radiative recombination dipole matrix elements of valence and subvalent levels of atomic Kr. The group delays along these transition channels are determined in the well-known Wigner-Smith approach, involving the energy derivative of the phases. A framework of time-dependent local density approximation is employed that utilizes the Leeuwen and Baerends exchange-correlation functional to produce accurate asymptotic behavior of ground and continuum wavefunctions [1]. Effects of dynamical correlations are found to significantly influence the phase and delay properties over most part of the spectra, particularly, in the vicinity of various Feshbach and shape resonances, as well as near the Cooper minima. Analysis of the TDLDA-derived complex induced potential reveals important insights.\\[4pt] [1] G. Dixit, H.S. Chakraborty, and M.E. Madjet, Phys. Rev. Lett.111, 203003, (2013). [Preview Abstract] |
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D1.00132: Parallel MicPIC for first-principle analysis of light-matter interactions in solids Charles Varin, Graeme Bart, Christian Peltz, Thomas Fennel, Thomas Brabec One of the main challenges in modeling laser-driven plasma physics is to properly resolve microscopic and macroscopic phenomena at the same time. For example, to resolve the propagation of a near-infrared pulse in a solid-density plasma, it is necessary to cover about four to five orders of magnitude in space---from {\AA} to $\mu$m---to resolve both the atomic collision processes and light propagation. Here, traditional tools like molecular dynamics (MD) and particle-in-cell (PIC) fall short. With MD, light propagation is neglected. With PIC, microscopic interactions are limited to small-angle binary collisions, which restricts its use to the weakly coupled (low density) regime. To overcome the limitations of MD and PIC, we developed the MicPIC approach. It is actually being optimized for large-scale computations to effectively allow tracking $10^{10}$ particles with atomic-scale resolution, along with light propagation. Moreover, custom physical models are being integrated into MicPIC to include on the atomic level the different ionization channels (single and multiphoton ionization, tunnel ionization, and electron impact ionization) and the atomic polarization due to bound electrons. This promises new insight into the physics of strong-field light-matter interactions in solids. [Preview Abstract] |
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D1.00133: Quantum phaseshifts and Wigner-Smith time delays in the photoionization versus radiative recombination of Ar valence electrons Maia Magrakvelidze, Gopal Dixit, Mohamed Madjet, Himadri Chakraborty Using a methodology of time-dependent local density approximation (TDLDA) [1] with the Leeuwen and Baerends exchange-correlation functional, the quantum phases of the amplitudes of photoionization (PI) and its inverse process of radiative recombination (RR) for various dipole channels of Ar have been calculated [2]. Energy differentials of the phases, the so called Wigner-Smith time delays, for processes involving valence 3p and 3s electrons are considered. TDLDA 3p recombination phases are found to concur well with the recent experiment [3]. Effects of electron correlations have been studied and diagnosed in the framework of dynamical coupling between degenerate configurations. Differences in the phase and delay structures between PI and RR are found in general with dramatic distinctions at resonances and Cooper minima in particular.\\[4pt] [1] M.E. Madjet, T. Renger, D.E. Hopper, M.A. McCune, H.S. Chakraborty, J.-M. Rost, and S.T. Manson, \textit{Phys. Rev. A} 81, 013202 (2010);\\[0pt] [2] G. Dixit, H.S. Chakraborty, and M.E. Madjet, \textit{Phys. Rev. Lett.}111$, $203003, (2013);\\[0pt] [3] S. B. Schoun, R. Chirla, J. Wheeler, C. Roedig, P. Agostini, L. F. DiMauro, K. J. Schafer, M. B. Gaarde, arXiv:1310.7008 [physics.atom-ph]. [Preview Abstract] |
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D1.00134: Recognition Tunneling of Biomolecules Predrag Krstic, Brian Ashcroft Complex bio-molecules, included DNA polymers, are localized, controlled and detected using a combination of electric fields, fluid flow through synthetic nanopores and tunneling current readouts, transversally to the pores. The key configuration element in the molecular recognition are bio-readers, developed by the Arizona State University, which establish hydrogen bonding with the molecule, which increases the tunneling current and slow down the molecule motion. The thermal fluctuations in the liquid causes a noisy tunneling readout. The recognition is achieved by learning vector machine. By computer simulation of the hydrogen bonding lifetime in presence of thermal fluctuations and using the vector machine analysis we reveal the details of the recognition tunneling in presence of strong noise. [Preview Abstract] |
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D1.00135: Smectic A to Nematic Phase Transition of the Aligned Octylcyanobiphenyl Could Bring Faster Response in Smectic Liquid Crystal Devices Dipti Sharma In the smectic liquid crystal devices, more attention has been paying to get smectic phase transition earlier with higher quality. The laser beam steering and the optical shutter applications have also been showing their interest on how fast the smectic phase transition can be reached. Therefore, here we report the energy dynamics of the molecular motion and rearrangement of the octylcyanobiphenly (8CB) liquid crystal molecules at the smectic A to nematic (SmA-N) phase transition in the presence of magnetic field alignment as a function of time, temperature and energy activation. The results indicate that the presence of the alignment in 8CB brings faster response time and an increased energy dynamics with higher activation for the SmA-N phase transition and make the results useful in the smectic liquid crystal devices. [Preview Abstract] |
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D1.00136: Proposal to verify the Jarzynski equality in a simulated open quantum system Jing-ning Zhang, Kihwan Kim We propose an experimental scheme to verify the Jarzynski equality in a simulated open quantum system. The Jarzynski equality first proposed by C. Jarzyski [1], relates the non-equilibrium work with the free energy difference, and has been therotically proved [2] for both closed and open quantum systems. There are several proposals as well as experiments concerning the verification of the Jarzynski equality in closed quantum system, while the experimental test in open quantum system still stay untouched. In our proposal, the system and environment are both simulated by simple harmonic oscillators, which can be readily implemented in a trapped ion system. We also propose a feasible way to reconstruct the work and heat distributions via the corresponding characteristic functions, which can be directly measured with the help of an ancilla qubit. \\[4pt] [1] C. Jarzynski, Phys. Rev. Lett. \textbf{78}, 2690 (1997).\\[0pt] [2] Shaul Mukamel, Phys. Rev. Lett. \textbf{90}, 170604 (2003). [Preview Abstract] |
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D1.00137: Plasmon and Exciton Coupling and Purcell Enhancement Quinton Rice, Maria Veronica Rigo, Rafal Fudala, Hyoyeong Cho, Wan-Joong Kim, Ryan Rich, Bagher Tabibi, Zygmunt Gryczynski, Ignacy Gryczynski, William Yu, Jaetae Seo The photoluminescence from plasmon-coupled exciton is of great interest for optoelectronic applications, because of the large quantum yield with localized field enhancement and reduced nonradiative transition. The Coulomb interaction through plasmon-exciton coupling results in the Purcell enhancement of quantum dots (QDs) in the vicinity of metal nanoparticles (MNPs). With plasmon-exciton coupling, the radiative and non-radiative decay rates and the coupling rates compete with each other. The coupling rate is closely related to the coupling distance between QDs and MNPs. The optimized coupling distance scales the re-excitation density of localized fields and the plasmon-exciton coupling rates. If the plasmon-exciton coupling rate is much faster than the radiative and non-radiative transitions of excitons, the re-excitations of excitons by the localized plasmonic field and the reduction of non-radiative transitions may occur. This presentation includes plasmon-exciton coupling dynamics, large enhancement and temporal properties of PL, and dipole-PL polarization fidelity of hybrid optical materials of plasmonic nanometals and excitonic semiconductor QDs. The work at Hampton University was supported by the National Science Foundation (NSF HRD-1137747), and Army Research Office (ARO W911NF-11-1-0177). The work at University of North Texas was supported by National Institutes of Health (NIH R01EB12003, and 5R21CA14897 (Z.G.)). [Preview Abstract] |
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