Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session F01: Poster Session I 4pm-6pm CDTPoster
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F01.00001: GPMFC Student Poster Prize Competition Finalists
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F01.00002: Exploring interactions in the band insulating regime with Fermi-degenerate 87Sr William R Milner, Ross Hutson, Christian Sanner, Lindsay Sonderhouse, Lingfeng Yan, Jun Ye Leveraging the SU(10) symmetric ground state of 87Sr for efficient evaporative cooling, we use a stark-shift-enabled spin selection technique to load a low-entropy, spin polarized gas into a 3D optical lattice. Using high intensity, in situ fluorescence detection we present results characterizing the 3D density distribution and filling fraction in the band insulating regime of our 3D lattice. This low-entropy, band insulator provides a unique optical lattice clock system for studying atomic coherence times, spin-orbit coupling, and dipolar interactions between atoms. We will present the latest progress on this clock platform. Additionally, experimental results demonstrating Pauli blocking in our Fermi-degenerate gas will be presented. |
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F01.00003: Generating High-Power Bragg Pulses for Atom Interferometry Andrew O Neely, Zachary R Pagel, Jack C Roth, Ocean Zhou, Weicheng Zhong, Holger Mueller Achieving lower systematic errors in atom interferometry calls for high-quality optical beams with large areas and therefore large optical powers. To this end, we are building a high-power quasi CW laser system, generating 250-μs pulses with up to 100-Hz repetition rate of light near the 852 nm D2 line of Cesium by amplifying a 500-mW Nd:YAG CW seed to produce up to 10 kW peak power at 1064 nm in 1 J pulses. This is converted to more than 7 kW of peak power at 532 nm using second harmonic generation in LBO. We will use this to pump optical parametric amplification in non-critically phase-matched LBO, seeded by light at 852 nm. This system is designed to deliver more than 1 kW peak power and should allow us to realize higher-order Bragg diffraction in our atomic fountain, a major step towards a higher precision measurement of the fine structure constant. |
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F01.00004: Improved magnetic shielding and coil systems for ACME III electron EDM search Siyuan Liu, Bingjie Hao, Daniel G Ang, David P DeMille, John M Doyle, Zhen Han, Ayami Hiramoto, Peiran Hu, Nicholas Hutzler, Daniel D Lascar, Zack Lasner, Takahiko Masuda, Cole Meisenhelder, John Mitchell, Cristian D Panda, Noboru Sasao, Satoshi Uetake, Xing Wu, Koji Yoshimura, Gerald Gabrielse The measurement of electron electric dipole moment (EDM) is a powerful probe for physics beyond the Standard Model. The ACME II Experiment in 2018 reported the current most stringent upper limit for electron EDM, of de<1.1×10-29 e·cm (Nature, 562, (2018) 355-360). The next generation of the experiment is currently under development, aiming to improve the sensitivity by at least an order of magnitude. This upgrade features a longer interaction region to increase the spin precession time, and significantly smaller magnetic-field-related noises. To achieve this, a custom-built 3-layer mu-metal magnetic shield covering a larger interaction region is under construction. With optimum geometric design and state-of-the-art degaussing systems, the shield is expected to reduce the ambient magnetic field to <0.1nT. A self-shielding coil and a set of gradient coils were also under construction, enabling the precise control of the magnetic field in the interaction region and the detailed assessment of systematic uncertainties associated with magnetic fields. |
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F01.00005: Precise measurements of trapped Cesium atoms in large electric fields Zhenyu Wei, Teng Zhang, David S. Weiss We have constructed an apparatus designed to measure the electric dipole moment (EDM) of laser-cooled cesium (Cs) atoms trapped in optical lattices. The apparatus can also measure other properties of Cs, including the ground state tensor polarizability (GSTP) and the differential Stark shift of the clock transitions. The Cs EDM measurement is sensitive to the electron EDM as well as other possible time reversal symmetry breaking electron-nucleus interactions. Since the GSTP is a third order effect, comparison of its measurement to calculations can be used to test parts of the atomic theory that is used to extract the weak charge from Cs parity violation measurements. The Stark shift measurement is proportional to the atomic response to the blackbody radiation, and so can be used to improve Cs clocks. We will describe our apparatus and explain our new Cs GSTP measurement, which represents a nearly two order of magnitude increase in precision over previous measurements. We will also discuss how we will carry out EDM measurements and differential Stark shift measurements with this apparatus. |
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F01.00006: Quantum enhanced optical atomic clock Chi Shu, Edwin Pedrozo-Peñafiel, Simone Colombo, Zeyang Li, Enrique Mendez, Albert Adiyatulline, Vladan Vuletic High bandwidth, high stability clocks offer unique chances to study fundamental physics beyond simple metrology. Optical atomic clocks which are primarily limited by the quantum projection noise have reached stability beyond 10-18. However, it took hours to average noise down to achieve such performance. Quantum state engineering on the other hand allows one to redistribute quantum noise. By combing the techniques of these two fields, an optical lattice clock with special quantum entangled state can reach the same stability at a much faster pace. With cavity feedback squeezing and coherent optical state transfer, we demonstrated entanglement on optical clock transition in 171Yb . We achieve a metrological gain of 4.4 dB beyond standard quantum limit. Recently, we are working on optimize our local oscillator laser locking to the a stable reference cavity. With a better performance of optical clock laser, we would be able to demonstrate a full operational quantum enhanced optical atomic clock. |
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F01.00007: COLLISIONS AND SPECTROSCOPY
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F01.00008: Absolute Hyperfine Energy Levels and Isotope Shift of Rb 5S – 6S Transition Carson McLaughlin, Seth Orson, Connor A Barberi, Mark D Lindsay, Randy Knize Using a Rb vapor cell and a wavemeter with a Doppler free two-photon transition near 993 nm, we have measured the hyperfine splittings of the 5S – 6S transition, and for the first time the 5S – 6S isotope shift to be 94 MHz, to an accuracy of 12 MHz. In doing so, we have measured the absolute energy levels of those 6S states to an accuracy of 60 MHz, five times more precise than the best previous measurements. We are proceeding to lock a microwave driven EOM sideband of our laser to an ultra-stable cavity, allowing a measurement of the hyperfine splittings and isotope shift of the 6S state to an accuracy of approximately 50 kHz. |
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F01.00009: Use of autoionization to measure microwave-driven transitions between high-n strontium Rydberg states Robert A Brienza The use of autoionization as a tool to measure transitions between high-n strontium Rydberg states with low-to-intermediate values of L is described and is demonstrated through observations of Rabi oscillations when driving 5snf 1F3 → 5s(n+ 1)g 1G4, 5snf 1F3 → 5s(n+ 2)h 1H5, and 5snp 1P1 → 5s(n+ 1)nd 1D2 transitions using microwave fields. The technique is shown to offer advantages when compared to selective field ionization, and can be used with other alkaline-earth and alkaline-earth-like metals. |
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F01.00010: Precision measurement of D2 line transition in a single trapped 25Mg+ ion Peng Hao, Zhiyu Ma, Wenzhe Wei, Zhuo Deng, Huixing Zhang, Liren Pang, Hongli Liu, Yuanbo Du, Wenhao Yuan, Ke Deng, Jie Zhang, Zehuang Lu Precision spectroscopy measurement plays a prominent part in the study of fundamental physical constants and atomic structure. In quasar absorption spectra, Mg+ ion doublet lines act as "anchor line" in the many multiplet method to find the time variation of fine structure constant α [1]. With the precision frequency data of Mg+ ions, we can get the isotope shifts of the three isotopes (mass number: 24, 25 and 26) and the hyperfine structure constants of 25Mg+. |
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F01.00011: Measuring the hyperfine structure within rubidium 5P3/2 excited-state using Saturated Absorption Spectroscopy Priyanka M Rupasinghe, Trieu N Le, Elina Van Kempen Motivated by testing the performance of a homemade external-cavity diode laser (ECDL) operating at 780 nm, the Saturated Absorption Spectroscopy (SAS) was performed to measure the hyperfine energy splittings of rubidium 5P3/2 excited state. Any nonlinearities associated with ECDL scans were removed by using a low-expansion confocal Fabry-Perot cavity and hence created a linearized frequency axis for the spectra collected in a fully automated fashion. Our results will be compared with the previous measurements reported in the literature. |
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F01.00012: Spectroscopy of highly charged Rydberg ions made by dielectronic recombination in few-electron Ar Timothy J Burke, Amy Gall, Yang Yang, Galen O'Neil, Paul Szypryt, Dipti Dipti, Joseph N Tan, Aung S Naing, Yuri Ralchenko, Endre Takacs, Joan Marler Rydberg Highly Charged Ions (RyHCI) are interesting systems to study as they provide excellent test beds for precision tests of quantum electrodynamics and precision X-ray wavelength standards. Moreover, certain high angular momentum states are considered to be potentially useful for measuring fundamental constants. Dielectronic Recombination (DR) is a significant process that results in the production of Rydberg states. We present X-ray spectra as a function of the electron beam energy that show the signatures of different processes populating electronic levels including DR. Measurements were done at the Electron Beam Ion Trap (EBIT) facility at the National Institute of Standards and Technology using an X-ray transition-edge sensor micro calorimeter. The Flexible Atomic Code (FAC) was used to identify the X-ray features related to the atomic processes involved. |
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F01.00013: Cavity-enhanced mid-infrared frequency comb spectroscopy: application to real-time ultra-sensitive breath analysis Ya-Chu Chan, Qizhong Liang, Jutta Toscano, P. Bryan Changala, David J Nesbitt, Jun Ye Exhaled breath analysis, by identifying biomarkers that reflect metabolic and physiological processes occurring in a human body, represents a promising approach for rapid, non-invasive medical diagnosis and disease monitoring. While mass-spectrometry-based methods are widely used to identify and quantify exhaled molecules, broadband laser spectroscopic techniques offer the possibility of simultaneous detection of multiple biomarkers with high detection sensitivity and specificity, but without the need for (1) gas chromatography to pre-separate various molecules and/or (2) routine calibration to achieve accurate quantification. This potentially in-situ and real-time analysis tool can become invaluable for medical applications. Here, we demonstrate a cavity-enhanced mid-infrared frequency comb breath analysis system with ultra-high detection sensitivity at parts-per-billion and even parts-per-trillion levels. With a wide spectral coverage from 2810 – 2945 cm-1, we can potentially detect at least ten clinically relevant biomarkers simultaneously, including CH3OH, CH4, H2CO, C2H6, C2H4, OCS, CS2, NH3, HDO, and H2O. To demonstrate the feasibility of applying this technique to real-time monitoring of human breath, we have tracked the concentration of molecules present in the exhalations of a volunteer before and after the consumption of ripe fruit, which reveals a consistent ≈ 0.15 ppm temporal increase in methanol concentration on the 1 – 2 hour time scale. |
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F01.00014: UV/VIS Spectroscopy of Ni I and II with Comparisons to Cometary Spectra Brynna Neff, Steven Bromley, Kumar Venkataramani, Dennis Bodewits, Joan Marler Laboratory-based spectroscopy of isolated atoms provides critical insight into astrophysical spectrum. Here we present UV/Vis spectroscopy of Ni I and Ni II. The measurements were performed at the Compact Toroidal Hybrid (CTH) plasma experiment at Auburn University. We report comparison of the observed lines with previous measurements as well as present on a number of previously unreported lines, the majority of which have been emitted from higher lying states due to the high electron temperature at the CTH. These laboratory spectra are expected to be relevant for analyzing the presence of metals, specifically nickel, in observed comet spectra. |
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F01.00015: High-Precision Faraday Polarimetry Measurements of Lead Transition Amplitudes and Static Polarizabilities John Lacy, Gabriel E Patenotte, Patrick Postec, Protik K Majumder We recently completed a direct measurement of the very weak (6s26p2) 3P0→3P2 939 nm electric quadrupole (E2) transition in atomic lead using an optical polarimeter with microradian resolution.1 A Faraday rotation spectroscopy technique was used to compare the transition strengths of the E2 transition to the (6s26p2) 3P0→3P1 1279 nm (M1) transition in a lead vapor cell heated to between 800 and 950 ̊C. We found excellent agreement with new ab initio theoretical calculations of relevance to parity nonconservation in lead. Using this highly-sensitive technique, we are now studying optical rotation signals in both an atomic beam apparatus, where we will measure the (6s26p2) 3P1→(6s26p7s) 3P0 368 nm (E1) transition using transverse (Doppler-narrowed) Faraday spectroscopy, and in a newly constructed heat pipe oven, whose enhanced sensitivity compared with the vapor cell will provide a boost to the 939 nm signal strength of more than an order of magnitude. We are now undertaking atomic-beam polarizability measurements of excited states of lead, as well as attempting a first direct measurement of the extremely weak (6s26p2) 3P0→1D2 466 nm (E2) transition in the heat pipe oven, both of which will serve as new, sensitive tests of atomic theory. Current experimental results will be presented. |
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F01.00016: PRECISION MEASUREMENTS
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F01.00017: Optical Control of Levitated Particles in A Thermophoretic Trap Huiting Liu, Kelsey Gilchrist, Michelle Chong, Cheng Chin We study the dynamics of levitated particles under illumination by a laser. Microspheres ranging from 10 to 50 μm in diameter are levitated and trapped in a thermophoretic force field generated in a vacuum chamber with air pressures between 4 and 15 Torr. The laser heats up and creates a temperature differential in the levitated particles. Momentum exchange with the surrounding gas drives the illuminated particles either in the direction of laser propagation (positive photophoresis) or opposite the direction of laser propagation (negative photophoresis). We report observations of both positive and negative photophoretic forces on levitated particles. To understand our experimental results vis-à-vis existing models of photophoresis, we simulate the radiation field and temperature distribution in levitated spheres to obtain quantitative predictions of the photophoretic and thermophoretic forces. This study of illumination-induced dynamics is a necessary first step towards optical control of levitated particles, which will find applications in studying micron-scale physics and force fields in a microgravity environment. |
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F01.00018: Update on a QED Book Project Ulrich D Jentschura, Gregory S Adkins For more than 60 years, the book of Bethe and Salpeter has been a cornerstone |
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F01.00019: Anisotropic rethermalization in ultracold thermal dipolar gases Reuben R Wang, John L Bohn Understanding the thermalization dynamics in ultracold gases is essential for its use in evaporative cooling and studies of many-body physics. In a dipolar thermal gas, it is primarily collisions which serve to facilitate thermalization, made intricate by their anisotropic differential cross section. We present theoretical methods to characterize the number of collisions per rethermalization [1], which for dipolar gases, are highly dependent on the dipole alignment axis. These methods are formulated to be easily applied in experimental contexts, and even reduce to analytic expressions if the route to thermal equilibrium is assumed as a single exponential decay. In the analytic case, collisional rethermalization is fully characterized by the dipole magnitude and orientation, scattering length, and excitation geometry. We characterize the extent to which our expressions are valid and compare their stipulated behavior to Monte Carlo simulations. |
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F01.00020: Ab initio investigation of the CO–N2 quantum scattering:The collisional perturbation of the pure rotational R(0) line in CO Hubert Jozwiak, Franck Thibault, Hubert Cybulski, Piotr Wcisło Collisions with the nitrogen molecule perturb the absorption lines of less abundant molecules in the Earth’s atmosphere, leading to the pressure broadening of the spectra which constitutes the primary broadening mechanism in the troposphere. Accurate values of pressure broadening and shift coefficients are essential for reducing atmospheric-spectra fit residuals, which might affect values of the quantities retrieved from the fit. This is especially important in terms of remote sensing of gaseous pollutants, such as the CO molecule. Accurate pressure broadening coefficients of the N2-perturbed CO lines are also needed in the analysis of the nitrogen-dominated atmospheres of Titan, Triton or Pluto. |
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F01.00021: A portable Rb quantum pressure standard for inter-standard validation Perrin Waldock, Pinrui Shen, Riley A Stewart, James Booth, Kirk W Madison Single atoms are ideal for metrology since they are ageless sensors operating on immutable laws of nature. Using atoms to measure vacuum pressure hinges on knowing the thermally-averaged loss cross section for collisions between the sensor atoms and the background gas particles. There are three ways to determine it: (1) estimate it using ab initio computations, (2) calibrate it using a known pressure for a known species against another accepted standard, or (3) measure it directly using the sensor atom and quantum diffractive universality (QDU).[1,2] We are collaborating with researchers at the US National Institute of Standards and Technology (NIST) to compare these three methods directly. To achieve this, we are building a portable version of our Rb-based pressure sensor calibrated using QDU (3) to send to NIST. It will be compared with their Li-based sensor (calibrated with (1)) and their orifice flow standard (2). This new apparatus uses magnetic quadrupole coils optimized to minimize thermal perturbations while maximizing the field gradient. The cooling, trapping, and detection light will be generated with an offset-locked laser and EOM to ease configuration. |
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F01.00022: Measurement of the loss rate coefficient for Rb-Rb collisions via Quantum diffractive universality Riley A Stewart, Pinrui Shen, Kirk W Madison, James Booth The loss rate of a magnetically-confined cold atomic ensemble is dominated by collisions with background particles at room temperature in the vacuum environment. For a single background species of density n, this rate can be written as Γ =n〈σv〉, where the loss rate coefficient〈σv〉depends on the magnetic trap depth U. For sufficiently shallow traps, the loss rate follows a single universal curve which we have previously reported for van der Waals interactions [New J. Phys. 21 102001 (2019), Metrologia 57 025015 (2020), Metrologia 58 022101 (2021)]. This description is defined by a single, experimentally determined parameter〈σtotv〉, the velocity-averaged total cross-section, which sets the loss rate coefficient at zero trap depth and the scale over which it varies, the quantum diffractive energy Ud. Here, we present loss rate measurements of Rubidium in a magnetic trap in the presence of a background, room temperature Rubidium vapour. This admits further verification by comparing loss rates using 87Rb or 85Rb as the trapped species. As Ud for these collisions is small, we compare the theoretically predicted and experimentally measured loss rate curves over a wide range of the scaled energy parameter U/Ud. |
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F01.00023: Bootstrapping quantum universality: Cross-species calibration of a cold atom pressure sensor Denis Uhland, Erik B Frieling, Pinrui Shen, James Booth, Kirk W Madison The atomic sensor is poised to become the first primary UHV pressure standard. The sensor ensemble loss rate is the density of background particles times the loss rate coefficient〈σlossv〉. Until recently, it was thought that〈σlossv〉could only be determined from knowledge of the interatomic potentials or from calibration with a known pressure. However, its universal dependence on trap depth allows an experimental determination of the characteristic ”quantum diffractive energy” (Ud) and thus〈σlossv〉for any background species. This self-calibrating feature opens up the possibility of measuring gases for which the calculation and calibration techniques are not feasible. Here we directly compare the self-calibrating method for 87Rb-H2 collisions with calculations of the 6Li+H2 cross-section. The 87Rb-H2 trap loss rate was used to determine the H2 background pressure and, subsequently, to determine the〈σtotv〉coefficient for 6Li-H2 collisions in a dual-species magnetic trap. This cross-calibration is necessary because Ud for 6Li-H2 collisions is large, limiting the precision to which〈σtotv〉can be determined via loss rate dependence. We compare our results to ab-initio calculations performed at NIST [PRA 99, 042704 (2019)], providing further evidence of the applicability of the self-calibrating technique. |
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F01.00024: Characterizing the Feshbach association of 23Na40K molecules Marcel Duda, Xingyan Chen, Andreas Schindewolf, Roman Bause, Xinyu Luo, Immanuel F Bloch The conversion of a mixture of Bose-Fermi atomic gases into fermionic Feshbach molecules, by sweeping the magnetic field across a Feshbach resonance, is limited by inelastic collisional loss. To characterize the loss during the association, we systematically measure the dimer-dimer, atom-dimer, and three-body loss in the 23Na-40K system and compare the loss with the zero-range scattering theory. We identify that the collisional loss between the sodium atoms and the Feshbach molecules is the bottleneck of the association. We observe surprisingly long-lived Feshbach molecules and a universal a^3 dependence of the fermionic dimer-dimer loss coefficient. Moreover, we observe a suppression of the three-body loss at unitary regime by Fermi degeneracy. These studies make it possible to prepare degenerate NaK Feshbach molecules. |
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F01.00025: Observation of Feshbach resonances in ultracold 23Na6Li+23Na collisions Yu-Kun Lu, Hyungmok Son, Juliana J Park, Michal Tomza, Tijs Karman, Alan Jamison, Wolfgang Ketterle Understanding molecular collisions in the quantum regime is the holy grail of quantum chemistry. Unfortunately, the high rovibrational density-of-states usually makes the collision process computationally intractable. As the lightest bi-alkali molecule, NaLi features relatively low density-of states which makes it an ideal platform to test quantum-scattering calculations. Furthermore, the long lifetime of NaLi in the triplet manifold also enables studies of spin-dependent molecular collision. In this work, we studied the dependence of NaLi+Na collision on external magnetic field over 1400G range and identified atom-molecule Feshbach resonances. By going close to the resonances, we are able to change the loss coefficient by more than order of magnetude. The observation of atom-molecule Feshbach resonance paves the way to study trimer physics in the future. |
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F01.00026: ULTRAFAST AND STRONG FIELD PHYSICS
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F01.00027: Generation of Optical Vortices with Strong Magnetic Fields for the Control of Nanoparticles Federico Roffé, Tilmann Kuhn, Guillermo Quinteiro Light can be spatially structured to enhance or reduce the interaction with particles. Optical vortices (OV) are a prominent example among structured beams, because of their possible new applications to materials science. An OV is a light field with phase singularities that carry orbital angular momentum, in addition to its spin angular momentum. Well-known examples of OVs with single phase singularities on the optical axis are Laguerre-Gauss and Bessel modes. Bessel beams are specially adequate for theoretical studies, because they are mathematically simple and represent paraxial as well as focused beams. We recently identified a large group of OV containing fields with varying degrees of relative strengths of electric (E) to magnetic (M) fields, parametrized by a real number γ. When γ = 0 the field at the optical axis (r = 0) has a constant E-field and a vanishing M-field. In contrast, for γ = 1 the M-field at r = 0 is constant and there is no E-field. A light beam of complex structure, such as an OV, can be decomposed into a superposition of plane waves. This modal decomposition or angular spectrum representation is useful to treat different problems, for example the propagation of structured light through interfaces using the well-known Fresnel coefficients. A γ = 1 field exhibits a dominant magnetic interaction with a particle placed at r = 0. This is magnetism at optical frequencies and it opens the way to more versatile control of particles. Here we show how a γ = 1 Bessel beam can be constructed as a superposition of plane waves. The decomposition allows us to explain how the beam can be generated in the lab using common optical elements. Furthermore, we clarify how one can measure, using an ion trap, the resulting γ = 1 beam emerging from the described optical system. Finally, we discuss possible uses of such a beam to the control of nanoparticles (e.g. quantum dots) or impurities (e.g. Eu3+). |
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F01.00028: Enhanced high-harmonic generation (HHG) from Cr-doped MgO crystals Francisco Navarrete, Viktoria Nefedova, Sven Fröhlich, Nicolas Tancogne-Dejean, Willem Boutu, Marcelo Ciappina, David Gauthier, Aimrane Hamdou, Shatha Kaassamani, Uwe Thumm, Hamed Merdji HHG from crystals is a new source of coherent extreme ultraviolet (XUV) attosecond radiation [1], which also allows the retrieval of band structure information [2]. Increasing the HHG yield and cutoff are fundamental to developing efficient XUV sources. We investigate an alternative way of boosting the HHG yield based on doping. The presence of dopants results in new electronic states in the band gap, as well as lattice defects, which modify the minimum band gap. Since the interband HHG yield depends exponentially on the minimum band-gap energy EG of the solid [3], one can expect a substantial change of the HHG yield by reducing EG [4]. We show the first experimental observation of impurity-enhanced HHG yields that is supported by our numerical solutions of the Semiconductor Bloch Equations [5]. |
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F01.00029: Time-resolved pump-probe spectroscopy with spooktroscopy Siqi Li, Taran Driver, Oliver Alexander, Bridgette Cooper, Douglas Garratt, Agostino Marinelli, James P Cryan, Jonathan Marangos Pump-probe spectroscopy with X-ray pulses provides us with the tool to generate atomic-level movies of ultrafast processes, such as chemical bonding and charge transfer, by varying the delay between the pump and the probe pulses. Spectral domain ghost imaging, or spooktroscopy, on the other hand exploits the intrinsic variation in the X-ray pulses and enables us to probe the spectral properties with superb resolution beyond the bandwidth limit. In this work, we demonstrate a clear separation of the pump signal from the probe signal even though they are tightly overlapped in energy. Furthermore, we also show a variation of the spooktroscopy reconstruction algorithm which applies regularization on the time domain, reconstructing a time-resolved pump-probe spectroscopy measurement. |
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F01.00030: The R-matrix with Time dependence approach RMT for atomic and molecular dynamics in intense fields Hugo W van der Hart, Andrew Brown, Gregory Armstrong, Daniel Clarke, Jack Wragg, Kathryn Hamilton, Jakub Benda, Zdenek Masin, Jimena D Gorfinkiel The R-matrix with time-dependence approach aims to solve the time-dependent Schrodinger equation for general multi-electron atoms and molecules interacting with intense laser light. In the last few years, we have generalised the approach to the treatment of arbitrarily polarised laser light, to the description of atoms within the Breit-Pauli approximation, and to the description of molecular dynamics. We will illustrate these developments through a demonstration of dynamics driven by the spin-orbit interaction, through verification of the ratio of emission of co- and counter-rotating electrons in circularly polarised light fields, and through the intensity dependence of photoionization of water. |
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F01.00031: Ionic Coherence in resonant ATI attosecond spectroscopy Saad Mehmood, Luca Argenti The ionization of atoms with sequences of attosecond pulses gives rise to excited ionic ensembles that preserve some coherence, despite their entanglement with the emitted photoelectron. In past theoretical studies of the pump-probe ionization of helium, we have shown that the loss of ionic coherence of the ions with the same principal quantum number N can be controlled by promoting multiphoton ionization from intermediate autoionizing states $N_Ln_\ell$, below the threshold, to the $N_{L'}\epsilon_{\ell'}$ continua~[1]. In the present work, we study the role played by the above-threshold $(N+1)_Ln_\ell$ resonances, which interact with the $N_{L'}\epsilon_{\ell'}$ channels due to correlation. |
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F01.00032: Theoretical treatment of quantum beats in the argon nf autoionizing states. Miguel Alarcon, Chris H Greene, Alexander C Plunkett, James K Wood, Arvinder S Sandhu An experimental poster, presented in parallel with this theoretical study, observes quantum beats between different autoionizing nf Rydberg states, as a function of the time delay between an ultrafast laser excitation of those states and a subsequent short laser pulse that can photoionize the nf states. To describe this experiment theoretically, multichannel quantum defect theory (MQDT) is implemented in combination with time-dependent perturbation theory to predict the observed oscillations in the angular distribution and in the angle-integrated energy-dependent photoelectron yield. Interference between the different quantum pathways as a function of the time delay results in an signal oscillating at frequencies equal to the difference between the quasi-discrete nf energies. The experimental signatures can be understood by including terms in the theoretical description up to second order in the field strength. This work was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0010545 |
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F01.00033: Autoionizing polariton stabilization in attosecond transient absorbtion Coleman B Cariker, Nathan Harkema, Eva Lindroth, Arvinder S Sandhu, Luca Argenti Intense laser pulses can couple resonances in the continuum, giving rise to a split pair of autoionizing polaritons whose lifetime can be extended as a result of interference between radiative and Auger decay channels [1]. We study this phenomenon both analytically and computationally by simulating ab initio attosecond transient absorption in argon. The calculated spectra exhibit multiple avoided crossings between the 3s-14p autoionizing resonance and light-induced states originating from other resonances. These avoided crossings, which are characteristic of the formation of a polaritonic multiplet, clearly indicate that some polaritons are stabilized against autoionization. Using an extension of the Jaynes-Cummings model to autoionizing states [2], we confirm that this stabilization is due to the destructive interference between radiative and Auger decay channels. These theoretical predictions are in excellent agreement with recent experiments conducted in parallel. This study indicates a new way to control the electronic structure in the continuum of poly-electronic systems. |
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F01.00034: Controlling non-adiabatic ionization with shaped ultra-short laser pulses Ulf Saalmann, Sajad Azizi, Jan M Rost Ultra-short, high-frequency pulses can drive non-adiabatic photoionization [1]. Fundamentally different from the conventional single-photon channel, the process is sensitive to the derivative of the pulse envelope. This renders non- adiabatic photoionization difficult to control at first glance. Here we device a route how to tailor this process by means of shaped pulses and/or quasi- resonant conditions in the atom, or more generally, the electronic system of the target. |
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F01.00035: Photoelectron spectroscopy of large water clusters ionized by an XUV comb Lorenzo Colaizzi, Loren Ban, Andrea Trabattoni, Vincent Wanie, Krishna Saraswathula, Erik Månsson, Philipp Rupp, Qingcao Liu, Lennart Seiffert, Elizabeth Herzig, Andrea Cartella, Bruce Yoder, Francois Legare, Matthias F Kling, Thomas Fennel, Ruth Signorell, Francesca Calegari Detailed knowledge about photo-induced electron dynamics in water is key to the understanding of several biological and chemical mechanisms, in particular for those resulting from ionizing radiation. We report a method to obtain photoelectron spectra from neutral water clusters following ionization by an extreme-ultraviolet (XUV) harmonic comb. Typically, a large background signal in the experiment arises from water monomers and carrier gas used in the cluster source. We report a protocol to quantify this background in order to eliminate it from the experimental spectra. We disentangle the accumulated XUV photoionization into contributions from the species under study and the photoelectron spectra from the clusters. This study demonstrates feasibility of background free photoelectron spectra of large water clusters illuminated with XUV combs and paves the way for the detailed time-resolved analysis of the underlying dynamics. |
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F01.00036: Investigation of electronic couplings with tunable, background-free, extreme-ultraviolet four-wave mixing Sergio Yanez-Pagans, Islam S Shalaby, Coleman B Cariker, Moniruzzaman Shaikh, Nathan Harkema, Luca Argenti, Arvinder S Sandhu Time-resolved four-wave mixing (FWM) spectroscopy is a versatile pump-probe technique which has been extended to the extreme-ultraviolet (XUV) regime in recent years. It is based on χ(3) parametric processes, in which the interaction of weak XUV attosecond pulse trains (APT) and strong-field near-infrared (NIR) femtosecond pulses with atoms or molecules captures information on the light-induced couplings between different quantum states. We start with helium as a prototypical atomic system where numerical modeling is feasible, and then generalize to study polyelectronic systems, such as krypton. Background-free XUV FWM signals are generated and easily isolated from the driving XUV spectrum by using non-commensurate NIR pulses. Moreover, the frequency tunability of the NIR pulse allows us to resonantly drive and selectively control the detuning from intermediate states, which gives us control over light-induced structures, Autler-Townes splitting, and coherent XUV FWM emissions. We also extend these studies to high-density regimes where collective effects play an important role. |
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F01.00037: Quantum Trajectory Selection via Strong Field Simulator Qiaoyi Liu, Andrew J Piper, Dietrich Kiesewetter, Pierre Agostini, Louis F DiMauro Strong field ionization and recollision is often described using a semi-classical model, whereby the electron first tunnels out of the atomic potential, then it is accelerated in the strong field, and finally it recollides with its parent ion. This three-step model assumes that electrons follow distinct classical trajectories in the second step that correspond to specific ionization times in the first. Past work on understanding this phenomenon has been limited, as the measured observables correspond to a superposition of all possible trajectories. We demonstrate the strong field simulator (SFS) method, which simulates strong field recollision by replacing the tunneling ionization step with single photon ionization from a sub-cycle extreme-ultraviolet (XUV) pulse with photon energies at or above the ionization threshold. By varying the delay between the strong field and the XUV pulse, the SFS will allow for unprecedented studies of individual classes of trajectories, as well as accessing new ones. These measurements could reveal quantum aspects absent in the classical description, along with observing novel light-matter interactions. Here, we will describe a new apparatus that will enable these studies, and discuss some initial results. |
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F01.00038: Energy, angle, and time-resolved probing of electron wavepacket dynamics with attosecond pulse trains and tunable laser pulses James K Wood, Alexander C Plunkett, Dakota J Waldrip, Dipayan Biswas, Miguel Alarcon, Chris H Greene, Arvinder S Sandhu We study the photoionization dynamics in atoms and molecules using tunable infrared laser pulses in conjunction with extreme ultraviolet (XUV) attosecond pulse trains. XUV excites a Rydberg wavepacket and delayed IR probe ionizes to produce photoelectrons which are analyzed in a time and angle resolved fashion with a velocity map imaging spectrometer. In argon, the tunable IR wavelength is used to control the outgoing electron energy relative to the two spin-orbit split ionization thresholds to investigate the contributions of different angular momentum states. We observed quantum beating in the delay-dependent yield for both ionization thresholds, albiet with a distinct phase difference between the two channels. The results are interpreted with a multi-channel quantum defect analysis of different pathways, which highlights importance of many-electron interactions in photoionization. The time and energy dependence of beta parameters is also analyzed in argon as well as other atomic and molecular systems. |
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F01.00039: Enhancing spin polarization using attosecond angular streaking Gregory Armstrong, Daniel Clarke, Jakub Benda, Jack Wragg, Andrew Brown, Hugo W van der Hart We use the R-matrix with time-dependence method [1-4] to investigate spin polarization of electrons ejected from the krypton atom by an angular streaking scheme. Through solution of the multielectron, semi-relativistic, time-dependent Schrödinger equation, we show that angular streaking produces strongly spin-polarized electrons. We find that the degree of spin polarization attainable using the angular streaking scheme exceeds that acheived using longer circularly polarized pulses. The degree of spin polarization increases with the Keldysh parameter, so that angular streaking --- ordinarily applied to investigate tunneling --- may be repurposed to generate strongly spin-polarized electron bunches. Additionally, we explore modifications of the angular streaking scheme that also enhance spin polarization. |
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F01.00040: ASTRA, a new close-coupling approach for single and double time-resolved molecular photoionization Luca Argenti, Nicolas Douguet, Heman Gharibnejad, Barry I Schneider, Juan M Randazzo, Jeppe Olsen Correlated electronic motion is at the core of light-induced chemical transformations. Until recently, attosecond science, which has opened the time-resolved study of electron dynamics, has focused on processes in which only a single extreme-ultraviolet (XUV) photon is absorbed and a single electron is liberated. New x-ray sources together with XUV-pump XUV/soft-x-ray-probe schemes promise drastically higher time resolutions. Soft-x-ray probes can excite localized core electrons, giving rise to new phenomena such as intramolecular photoelectron scattering and multiple photoionization. The theoretical description of these processes resolved in time will be key to track the motion of correlated electron pairs. Here we present a new approach to the time-dependent close-coupling scheme for single and double multichannel molecular photoionization and an implementation of the single ionization in the new ASTRA (AttoSecond TRAnsitions) code. ASTRA structural algorithms are based on established hybrid gaussian-numerical bases and on higher-order transition density matrices (TDM) between arbitrary-spin excited ionic states of the target molecule. The TDMs are computed using a general-active-space formalism, and can treat ionic states obtained from large-scale CI calculations. Preliminary results will be presented for the N2 molecule, together with comparison with CI-singles benchmarks. |
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F01.00041: Ultrafast Laser-Induced Isomerization Dynamics in Acetonitrile Matteo McDonnell, Aaron C LaForge, J. Reino-Gonzalez, Nora G Kling, Debardashini Mishra, Razib Obaid, Vit Svoboda, Sergio Díaz-Tendero, Fernando Martin, Nora Berrah We will present the investigation of acetonitrile (CH3CN) isomerization induced by laser ionization using pump-probe spectroscopy paired with ion-ion coincident Coulomb explosion imaging. Five primary channels indicating direct C-C breakup, single and double hydrogen migration, and H and H2 dissociation in the acetonitrile cation were found. Unexpectedly, the hydrogen-migration channels dominate over direct fragmentation. This observation is validated by quantum chemistry calculations showing that isomerization through single and double hydrogen migration leads to very stable linear and ring isomers, most of them more stable than the original linear structure following ionization of the parent molecule. This is distinct from a previous investigation on ethanol using similar experimental technique. We have also determined the timescales of the corresponding dynamical processes by varying the delay between the pump and probe pulses and found that the isomerization occurs within a few hundred femtoseconds. |
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F01.00042: Multidimensional Multimodal Molecular Motion Viewed With Hard X-rays Ian Gabalski, Matthew R Ware, Michael Minitti, Ruaridh Forbes, Kyle Acheson, Philip H Bucksbaum Polyatomic photoexcited molecules exhibit many competing modes of atomic motion, such as bending, stretching, and dissociation. The coupling of these modes leads to a wide variety of reaction pathways which are poorly described by present state-of-the-art theory. Time-resolved X-ray scattering (TRXS) can spatially and temporally resolve the complex atomic motion of such photoexcited molecules. Here we study the intramolecular motion of CS2 following photoexcitation at 200 nm using TRXS with 9.8 keV X-rays at LCLS. CS2 excited at 200 nm exhibits both symmetric stretch and bending motion followed by dissociation into multiple exit channels. These types of motion are best viewed in the frequency-resolved basis S(Q,ω), where they appear as sparse features with simple interpretations. We employ the Lomb-Scargle periodogram to view our noisy, non-uniformly sampled data in this basis, and observe both vibrational and dissociative motion. Sliding the transform window over a subset of the data enables identification of the onset of vibrations and subsequent coupling to dissociation channels. |
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F01.00043: Ultrafast dynamics of photoexcited carriers in vapor-phase fullerene Esam A Ali Understanding of the hot electron relaxation dynamics through intraband transitions in fullerene materials is invaluable in organic photovoltaics applications. In this work, we investigate the hot carrier relaxation of photoexcited C60 molecule by using a scheme of ab initio non-adiabatic molecular dynamics simulations based on density functional theory [1-2]. The methodology is underpinned by a combination of the fewest-switch surface hopping approach and Kohn−Sham single-particle description [1]. Results indicate the relaxation of the excited population to the band edges that occurs on the ultrafast time scale driven by the dynamical electron-phonon coupling. The population lifetimes of the intermediate states largely map out the unoccupied ground state spectrum which may motivate experimental interests. |
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F01.00044: Ultrafast Hydrogen Migration and Fragmentation Dynamics in 1- and 2-Propanol Debadarshini Mishra, Juan Gonzalez, Razib Obaid, Aaron C LaForge, Sergio Díaz-Tendero, Fernando Martin, Nora Berrah We present a comparative study of laser-induced fragmentation and hydrogen migration dynamics, triggered through ionization, for the two structural isomers, 1-propanol and 2-propanol. Using pump-probe spectroscopy in combination with coincident ion-momentum imaging techniques, we identify the channels showing direct breakup and single/double hydrogen migration for both the isomers. We extract the kinetic energy release (KER) as a function of pump-probe delay, which helps determine the timescales of the different processes. Interestingly, we observe different features in the KER for the two isomers, indicating different reaction pathways resulting in the same final ionic fragments. Our experimental results are interpreted by state-of-the-art ab initio molecular dynamics calculations. |
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F01.00045: Dynamics of dissociation and photoionization by VUV and XUV photons revealed by ion fragment and photoelectron momentum imaging Daniel Slaughter, Kirk A Larsen, Roger Y Bello, Felix Sturm, Muhammad A Fareed, Niranjan Shivaram, Ali Belkacem, C W McCurdy, Thomas N Rescigno, Robert R Lucchese, Predrag Ranitovic, Thorsten Weber We report recent progress on interrogating the highly-coupled electronic and nuclear dynamics in small molecules using vacuum- and extreme-ultraviolet pulses to excite, control and probe transient molecules on excited electronic states. A detailed understanding of photoionization mechanisms in these systems necessitates the ability to clearly distinguish metastable electronic states in the ionization continuum from direct photoionization [1]. Photoelectrons and fragment ions are analyzed by high-resolution cold target recoil ion momentum imaging (COLTRIMS), to identify and investigate these different pathways by the kinetic energy-resolved photoelectron and fragment angular distributions [2]. |
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F01.00046: Alignment-dependent photoelectron angular distributions in few-photon ionization of molecules by ultra-violet pulses Huynh Van Sa V Lam, Tomthin Wanjam, Vinod Kumarappan We used velocity map imaging to investigate the time-dependent ionization dynamics of impulsively-excited rotational wave packets of N2, CO2, and C2H4 probed by broadband UV pulses (≈ 262 nm). Photoelectron momentum distributions show a strong dependence on alignment, on multiphoton order, and on the electronic and vibrational states of the cation. We show that, without prior knowledge of the photoionization process, partial but substantial information about the molecular-frame photoelectron angular distributions can still be retrieved from the highly-anisotropic laboratory-frame data using a fitting algorithm. We also compare few-photon ionization with single-photon ionization and strong-field ionization. In many cases, we found similarities between the angle-dependent ionization rates by few-photon and by a strong field. On the other hand, the photoelectron angular distributions in few-photon ionization are very sensitive to molecular structure and dynamics, which is similar to single-photon ionization. |
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F01.00047: Direct Electric Field Reconstruction of Femtosecond Time-Resolved Four-Wave Mixing Signals Francis F Walz, Siddhant Pandey, Varadharajan Muruganandam, Niranjan Shivaram We describe a method to measure the real and imaginary parts of the third order non-linear response in molecules and materials by directly measuring the electric field of four-wave mixing signals. We use the four-wave mixing process of Optical Kerr-effect (OKE) to measure the nonlinear response and use the TADPOLE (Temporal Analysis by Dispersing a Pair of Light E Fields) technique to reconstruct the electric field of the weak four-wave mixing signal. Typically, the real and imaginary parts of the third-order nonlinear response are measured in a heterodyne scheme using a local oscillator as a reference field. Such measurements, especially when adopted in ultrafast time-resolved experiments, can be cumbersome. Our method of direct electric field reconstruction of the nonlinear signal makes these measurements much simpler without requiring a heterodyne scheme. We demonstrate this method by reconstructing the electric field of OKE signals in carbon dioxide gas and fused silica glass. These studies are an important step towards complete measurement of the third-order non-linear response for probing ultrafast dynamics in molecules and materials. |
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F01.00048: Comparative studies of surface hopping method for molecules in few-cycle intense laser pulses Phi-Hung Tran, Hung Hoang, Anh-Thu Le We present theoretical investigation of different versions of the semiclassical surface-hopping method for the simulation coupled electron-nuclear dynamics in the present of ultrafast intense laser pulses. We analyze the detailed comparisons of the method together with the exact numerical solutions of the coupled-channel time-dependent Schrodinger equation (TDSE) for a few different benchmarked systems for molecular dissociation as well as a realistic system of intense infrared pump -- intense infrared probe in O2. Our results indicate that with proper choices of the hopping criterion, the surface hopping method is capable of reproducing results comparable with the exact TDSE for molecules in few-cycle intense infrared or mid-infrared laser pulses. |
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F01.00049: QUANTUM INFORMATION AND QUANTUM OPTICS
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F01.00050: Conservation of orbital angular momentum and extremal ellipticity for simple and general astigmatic Gaussian beams Duc H Le, Arpita Pal, A. Qadeer, M. Kleinert, J. Kleinert, S. Goel, K. Khare, M. Bhattacharya Orbital angular momentum (OAM) of light depends on the spatial electric field amplitude and the phase structure of the beam wavefront. Light beams possessing finite OAM have been actively investigated in the context of particle micro-manipulation, microscopy, quantum informatics, etc. Recently Lo et al. [1] showed that the extremal ellipticity for a simple and general astigmatic Gaussian beam is conserved upon propagation through a rotationally invariant optical system, such as a sequence of stigmatic lenses. Here we carry forward this work and theoretically demonstrate that the conservation of extremal ellipticity for an astigmatic Gaussian beam propagating through such a medium is a direct but nontrivial consequence of the conservation of OAM of the beam. We present explicit analytical expressions for the first few moments of the beam OAM and report that apart from fundamental constants, they depend only on the beam's extremal ellipticity. Our work is expected to find use in areas where the ellipticity of the Gaussian beam is important, such as laser micromachining, lithography and imaging. |
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F01.00051: Optical nonreciprocity and unidirectional transmission by loss engineering xinyao huang As the basic units in optical systems, nonreciprocal devices play important roles in optical communication and optical information processing. They prohibit a light field from returning along its original path after passing through an optical system in one direction, implying the breaking of the Lorentz reciprocity theorem. Conventional principles for realizing nonreciprocity rely on magneto-optical properties (e.g. Faraday rotation). However, the magnetic fields required make it difficult for integration on a small scale. To overcome this problem, it is crucial to realize optical nonreciprocity also unidirectional energy transmission by developing magnetic-free approaches. In this work, we will propose and analyze a generic method to nonreciprocity generation by loss engineering. When multiple dissipative coupling channels exist, the phase lag induced by the loss, results in different interference outcomes to implement nonreciprocity and unidirectional energy transmission. This study paves the way for nonreciprocal device design in lossy systems without stringent conditions and provides opportunities for studying chiral and topological properties in systems with lossy coupling. |
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F01.00052: Polarization-Independent Active Switch Leo Y Oshiro Effectively transmitting quantum information in a quantum network necessarily involves switching, delaying and routing the optical signals. Using polarization states to encode quantum information requires a switching mechanism that preserves the polarization of the incoming signal, and switches without introducing unnecessary loss. We use an optical setup that allows the active switching of a pulsed arbitrarily polarized signal by setting the voltage applied to a Pockel's cell. Free-space measurements show that our setup is able to achieve efficiencies of 87-90%, while maintaining extinction ratios of 100:1. Preliminary quantum process tomography measurements show that the router can maintain the purity of any input quantum state at the 99% level when coupled into single-mode fiber. |
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F01.00053: Photon induced atom recoil in collectively interacting planar arrays Deepak Aditya Suresh, Francis J Robicheaux We study the recoil of atoms due to the emission or absorption of photons in atomic arrays with sub-wavelength interatomic spacing. The atoms in the array interact with each other through collective dipole-dipole interactions and with the incident laser field in the low intensity limit. Shining uniform light on the array gives rise to interesting patterns of excitation and recoil in the array. These arise due to the interference of different eigenmodes of excitation. We study the recoil effects of these eigenmodes and the directional properties of the recoil. The recoil experienced by the array was found to be proportional to the lifetime of the excitation eigenmode, i.e., a subradiant collective decay experiences a substantially larger recoil than from independent atom decay. Pronounced recoil effects can also be seen in highly subradiant cavities made of two curved atomic arrays. We further describe a method to calculate the rate of recoil energy deposited in a steady state situation with a constant incident laser. |
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F01.00054: Polarization-Modulator based Quantum Key Distribution (QKD) Source Tahereh Rezaei In this effort, we present progress towards demonstrating a Decoy-State Quantum Key Distribution (QKD) source which is based on a polarization-modulator and an attenuated pulsed laser that is wavelength stable. A three-state QKD protocol is achieved by the preparing the polarization of the quantum state. The polarization-modulator based QKD source improves security by eliminating several sources of side-channel attacks which are present when using multiple sources to produce different QKD states. The QKD source design is presented along with evaluation of critical subsystems, and the performance is characterized including Quantum Bit Error Rate (QBER), Quantum State Tomography, and achievable Key Rates. The QKD source is designed to operate under compact Size, Weight, and Power (SWaP) limitations. Applications of the Polarization-Modulator QKD source include deployment in future mobile quantum networks including Unmanned-Aerial Vehicles (UAV) and autonomous vehicles, in addition to fixed fiber-based quantum networks. |
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F01.00055: Wavelength Conversion of Quantum Dot Photons with Cold-Cs Atoms in a Hollow-Core Fiber Divya Bharadwaj, Sai Sreesh Venuturumilli, Paul Anderson, Rubayet Al Maruf, Michael Reimer, Michal Bajscy Solid-state emitters, such as quantum dots, interfaced with cold atomic ensembles can be used to explore novel quantum optics protocols based on single photon nonlinearities. For instance, a quantum state-preserving conversion of photons from one frequency to another can serve as a key networking and information processing element. In this project, we aim to develop an interface between a InAsP quantum dot (QD) embedded in semiconductor nanowire (InP) and laser-cooled Caesium (Cs) atoms confined inside hollow-core fibers. As a precursor framework, we theoretically investigate the conversion of short (~ 1 ns) photon pulses emitted by the quantum dot (894.6 nm) to a S-band telecom wavelength (1469 nm) and a wavelength suitable for satellite-based QKD (794 nm) using four-wave-mixing in the fiber confined Cs cloud. We present analytical and numerical simulation results that specify conditions of the applied laser fields and atom cloud necessary to realize efficient and purity-maintaining wavelength conversion. The platform of laser-cooled atoms in hollow-core fibers helps us in meeting the requirements of applied field powers and high optical depths. |
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F01.00056: Comparison of frequency conversion processes in rubidium vapor Mirela A Gearba-Sell, Carson McLaughlin, Seth Orson, Randy Knize, Mark D Lindsay, Jerry F Sell Exploiting nonlinear optical processes in a Rb vapor, we describe the generation of optical fields at 420 nm, 1.32 µm, and 1.37 µm. Laser beams at 780 nm and 776 nm, collinear and circularly polarized, enter a heated Rb vapor cell. Rubidium atoms are excited to the 5D5/2 state, with blue light at 420 nm generated by four-wave mixing through the 6P3/2 → 5S1/2 states, while infrared beams at 1.37 µm and 1.32 µm are generated by cascading decays through the 6S1/2 → 5P3/2 and 6S1/2 → 5P1/2 states, respectively. While the collimated blue light emission from four-wave mixing has been studied in detail, the mechanisms responsible for generating the infrared beams are less understood. We will present our results for the conditions that give rise to infrared beam generation by two-photon excitation in rubidium vapor. |
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F01.00057: Frequency conversion through Rydberg states Erik G Brekke We explore the possibility of frequency conversion using four-wave mixing through Rydberg states in rubidium. Excitation is accomplished through the intermediate 6p state using light at 420 nm generated through parametric four-wave mixing in combination with a 1015 nm laser. When combined with a 780 nm laser, four-wave mixing through the Rydberg state can generate a beam at 480 nm. Even more promising is the potential to use six-wave mixing to accomplish microwave to optical frequency conversion. Microwaves resonant with a transition between nearby Rydberg states can cause the creation of light in the infrared. Several possible methods for accomplishing this conversion are outlined. |
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F01.00058: Laser System for the MAGIS-100 Long Baseline, Strontium Atom Interferometer Kenneth DeRose, Tejas Deshpande, Tim Kovachy To this day, dark matter continues to evade detection by our most advanced sensors. Most experiments have focused their search on WIMPs, but astrophysical observations are also consistent with the existence of ultra-light dark matter particles. MAGIS-100 is 100-meter atom interferometer currently being built at Fermilab which will search for oscillations in fundamental constants and time-dependent, equivalence-principle-violating accelerations of test masses: key signatures of several ultra-light dark matter candidates. This presentation will feature our progress on the MAGIS-100 project with a focus on the laser systems and laser manipulation techniques used to generate meter-separated quantum atomic superpositions in the interferometer. We will include details on two laser operation modes, respectively involving coherent combination of two 698 nm lasers for exciting Sr clock transitions (searches for oscillating fundamental constants) and two independent 679 nm lasers for Bragg transitions in two Sr isotopes (searches for oscillating accelerations). In addition to dark matter searches, the interferometer can adapt toward searches for new fundamental forces outside the Standard Model, tests on the coherence limits of spatially separated wave packets. It will also serve as a prototype gravitational wave detector in frequency band between the peak sensitivities of LIGO and LISA. |
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F01.00059: QUANTUM INFORMATION SCIENCE
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F01.00060: Prerequisites for time emergence in quantum and classical mechanics Sebastian Gemsheim, Jan M Rost Is time fundamental or emergent? This is an old question but to date the answer remains elusive. Advocating for the latter, we put forth a set of basic prerequisites necessary for its emergence and examine their implications in quantum and classical mechanics. |
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F01.00061: Quantum to Classical Walk Transitions Tuned by Spontaneous Emissions Jerry H Clark, Yingmei Liu, Gil Summy, Sandro Wimberger, Caspar Groiseau, Zachary N Shaw, Siamak Dadras, Cosmo Binegar We have recently realized a quantum walk in momentum space with a rubidium spinor BoseEinstein condensate by applying a periodic kicking potential as a walk operator and a resonant microwave pulse as a coin toss operator. The generated quantum walks appear to be stable for up to ten steps and then quickly transit to classical walks due to spontaneous emissions induced by laser beams of the walk operator. We investigate these quantum to classical walk transitions by introducing well-controlled spontaneous emissions with an external light source during quantum walks. Our findings demonstrate a scheme to control the robustness of the quantum walks and can also be applied to other cold atom experiments involving spontaneous emissions. |
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F01.00062: Toward quantum control and metrology with an ultracold cesium atom array Hoang Van Do Ultra-cold neutral atoms, with their long coherence times and weak coupling to laboratory noise, constitute an excellent platform for experiments in quantum state control and metrology. We are developing a new experiment to generate and control large, entangled spin states for this purpose using ultracold neutral cesium atoms held in optical tweezers. Such a platform can be used for investigating quantum logic gate protocols and the boundaries of experimental robustness and computational complexity. We will present our recent experimental progress. |
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F01.00063: Many-body non-equilibrium phenomena with a Trapped-Ion Quantum Simulator Visal So Trapped atomic ions are one of the leading platforms for the simulation of spin models. Here we present our progress on the construction of a multi-species trapping apparatus for Ytterbium and Barium ion chains. The system is based on a segmented four-blade Paul trap, which provides a large numerical aperture for high-resolution imaging (NA~0.6) and individual addressing (NA~0.3). The electrodes have been devised to optimize the homogeneity of the confinement radiofrequency field along the trap axis and to lower the required voltage to achieve quasi-uniformly spaced ion chains. We will also report our effort to extend this trap design to a monolithic three-dimensional trap with high precision electrode alignment utilizing laser writing and controlled glass etching techniques. By using internal electronic states within each ion to encode spin degrees of freedom and the normal phonon modes of the ion chain to tailor the interactions among the qubits, we aim to efficiently investigate spin Hamiltonians beyond the ability of classical computers. The apparatus is designed to give us precise control of both unitary and dissipative evolutions of the spin systems, allowing us access to new frontiers of quantum simulation, including the realization of quantum spin glass models and the study of lattice gauge theories. |
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F01.00064: Quantum Computing Operations via Hamiltonian Engineering in Ultracold Neutral Atoms Joseph Lindon, Arina Tashchilina, Logan W Cooke, Tian Ooi, Taras Hrushevskyi, Benjamin D Smith, Lindsay J LeBlanc Neutral atoms are a versatile platform for quantum simulation, where a desired Hamiltonian is engineered by tuning interactions between states. In this work, we explore possible quantum computing operations in ultracold 87Rb, including those with non-trivial topological character. Our apparatus couples atomic states via optical, microwave, and modulated magnetic fields. We create Raman coupling between states with ΔmF of 1 or 2 by sending two beams with appropriate polarizations and a tuned frequency difference. In some cases, we can dynamically change the manifold dimensionality of the interacting system, as Raman coupling to specific states is suppressed via destructive interference between interaction paths. We also use microwave sources to directly couple between hyperfine levels, and we adjust the splitting between Zeeman sublevels by changing the strength of an external magnetic field. We combine these schemes to achieve useful Hamiltonians for quantum computing applications. Once computing operations are complete, we measure the output by Stern-Gerlach imaging. Typically, fully characterizing a qubit state requires several measurements to determine x-, y-, and z-populations. Here, we explore full state characterization by coupling to a higher dimensional manifold before imaging. |
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F01.00065: A Rydberg Programmable Quantum Simulator with 256 Qubits Tout T Wang, Sepehr Ebadi, Harry Levine, Alexander Keesling, Giulia Semeghini, Ahmed Omran, Dolev Bluvstein, Rhine Samajdar, Hannes Pichler, Wen Wei Ho, Soonwon Choi, Alexios Michailidis, Nishad Maskara, Maksym Serbyn, Subir Sachdev, Markus Greiner, Vladan Vuletic, Mikhail Lukin The realization of programmable quantum many-body systems capable of coherently controlling hundreds of individual particles is one of the frontiers of quantum science and engineering. Such systems provide unique insights into exotic quantum states of matter and enable new approaches to quantum computation. Our platform at Harvard consists of 2D arrays of laser-cooled neutral atoms trapped in optical tweezers. Using coherent coupling to highly-excited Rydberg states, we realize a quantum spin model with tunable long-range interactions for system sizes up to 256 qubits. With this platform, we have recently realized high-fidelity antiferromagnetically ordered states, mapped out the square-lattice phase diagram, and demonstrated the universal properties of an Ising quantum phase transition in (2+1) dimensions. Separately, we have also observed non-equilibrium quantum many-body scar dynamics after rapid quenches of 2D antiferromagnetically ordered states, and showed that these scars can be stabilized by periodic driving that generates a robust sub-harmonic response akin to discrete time-crystalline order. Ongoing efforts include quantum optimization of graph problems that can be encoded efficiently in our system, and realizing exotic entangled states of matter on frustrated lattices. |
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F01.00066: Progress in exploring infinite-range many-body physics in a strontium cavity-QED platform Dylan Young, Julia R Cline, Vera Schäfer, James K Thompson When atoms with a narrow-linewidth transition are collectively coupled to a detuned optical cavity, they exhibit an effective spin-spin interaction which has infinite range [1]. Previously, we demonstrated that competition between these spin-exchange dynamics and an external drive along the 1S0-3P1 transition in 88Sr leads to a dynamical phase transition [2]. Current efforts are focused on extending this physics to a multilevel system by allowing atoms to populate different Zeeman sublevels of the excited state. Through a combination of QND-style probing through the cavity and heterodyne measurements of the atoms’ self-radiated field, we expect to observe three distinct dynamical phases in analogy to phases in a BCS superconductor [3]. |
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F01.00067: Towards a large scale fully programmable trapped-ion quantum information processor Chung-You Shih, Nikhil Kotibhaskar, Sainath Motlakunta, Anthony Vogliano, Roland Hablützel, Rajibul Islam Long coherence times, high fidelity qubit state initialization and detection, and programmable long-range interactions make trapped ions a leading platform for quantum information processing (QIP). Here, we describe our recent development of a large-scale trapped-ion based quantum information processor. It is equipped with a multi-segmented blade electrode ion trap capable of trapping a large (>50) chain of Ytterbium ions in a near uniformly spaced configuration. Optimal vacuum system engineering has allowed us to design a vacuum vessel with simulated pressures of at least one order of magnitude lower than current room temperature trapped ion quantum information processor. A high numerical aperture (NA) holographic optical addressing system will be used for aberration-corrected addressing of the trapped ions with minimal 'crosstalk error' [1]. Such high-precision optical control will enable a wide range of QIP experiment from quantum simulations of reprogrammable, dynamical, and arbitrary lattice geometry of spins to researching problems in quantum error correction code. |
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F01.00068: Many-body XXZ Ramsey dynamics in a tunable NV simulator Leigh S Martin, Hengyun Zhou, Nathaniel T Leitao, Nishad Maskara, Oksana Makarova, Matthew Tyler, Alec Douglas, Joonhee Choi, Soonwon Choi, Hongkun Park, Mikhail Lukin Dense, interacting ensembles of NV centers in diamond not only offer state-of-the-art sensing capabilities under ambient conditions, but also present a unique quantum simulation platform for long-ranged quantum magnetism. In particular, Ramsey dynamics provide a simple probe of many-body spin systems out of equilibrium, and can yield metrologically useful spin squeezed states if suitably controlled. We present recent experimental data and numerical simulations on the Ramsey dynamics as a function of the anisotropy parameter in the paradigmatic XXZ Hamiltonian. Although heuristic arguments in the NMR literature predict pure exponential decay of uniformly polarized states for all underlying XXZ Hamiltonians, we observe striking features near the XY and Heisenberg Hamiltonians. We describe theoretical progress toward understanding these features as a consequence of emergent collective behavior. We also highlight our recent innovations in pulse sequence design that enable these measurements, which should be applicable to many other physical systems. |
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F01.00069: New Directions in Quantum Simulation with Trapped Atomic Ions Kate S Collins, Patrick M Becker, Arinjoy De, Antonis Kyprianidis, Wen Lin Tan, Tianyu You, Lei Feng, William N Morong, Guido Pagano, Christopher R Monroe The high-degree of isolation and controllability in a trapped ion system makes it a natural platform for quantum simulation. We coherently control and manipulate 15-25 171Yb+ ions confined in a three-layer linear rf Paul trap. Using global Raman beams we engineer tunable spin-spin interactions, which are combined with transverse and longitudinal effective magnetic fields to realize a long-range Ising model. We combine this with a site-dependent effective Bz magnetic field from a tightly focused beam, allowing for initialization of arbitrary product states or creation of a programmable site-dependent field. Harnessing these coherent operations and site-resolved detection, we present recent experiments implemented on this trapped-ion quantum simulator, exploring non-equilibrium phases and toy models of high-energy physics phenomena. |
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F01.00070: Engineering Programmable Interactions with an Optical Cavity Eric S Cooper, Philipp Kunkel, Avikar Periwal, Emily J Davis, Julian F Wienand, Monika H Schleier-Smith Tuneable, long-range interactions facilitate the study of quantum phenomena including integrability and fast scrambling. In our system, a driven optical cavity naturally mediates all-to-all interactions along a 1D chain of atomic ensembles. We break the global symmetry of these interactions by adding a gradient that dephases interactions between spatially separated ensembles. Interactions at specified distances are selectively re-introduced by modulating the drive field. Local addressing and in-situ imaging facilitate detailed exploration of dynamics on effective geometries specified by the graph of couplings. Realized geometries include 2D surfaces and a Moebius ladder, and we find that the dynamics are well described by the engineered dispersion relation. Current directions include probing entanglement and frustrastration in varied interaction graphs with applications in precision measurement and quantum simulation. |
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F01.00071: Towards a dual-species Rydberg atom quantum simulator Fang Fang, Kenneth Wang, Yu Wang, Avery Parr, Yichao Yu, Kang-Kuen Ni Neutral atoms in optical tweezer arrays have emerged as a powerful and flexible platform for quantum science, allowing for the study of quantum spin models and high fidelity quantum logic operations. These individually trapped and detected atoms interact strongly and controllably via excitation into Rydberg states. Current efforts have mostly focused on using a single atomic species, but using two species offers several advantages. Substantially different resonant frequencies of the two species allow excellent spectral resolution, providing low cross talk qubits with a few microns spacing. Moreover, the interaction between two elements can be tuned via the Rydberg states they are excited to, providing an extra degree of freedom for quantum simulators. In addition, one species can act as an auxiliary qubit to manipulate and measure the quantum state of the qubits formed by the other species. We are working towards a dual-species Rydberg quantum simulator, based on deterministically prepared optical tweezer arrays of ground state cooled Na and Cs atoms. Excitation to various Rydberg states with different interaction potentials is also being explored and implemented. |
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F01.00072: Spin transport and transverse spin dynamics in a tunable Heisenberg model realized with ultracold atoms Niklas Jepsen, Wen Wei Ho, Jesse Amato-Grill, Ivana Dimitrova, Eugene Demler, Wolfgang Ketterle Simple models of interacting spins play an important role in physics. The field of quantum simulation aims at implementing such systems in a controlled and tunable way. So far, spin transport has only been studied in systems with isotropic spin–spin interactions. Here we realize the spin-1/2 anisotropic Heisenberg model, with fully adjustable anisotropy of the nearest-neighbour spin–spin couplings (called the XXZ model). In this model we study spin transport far from equilibrium after quantum quenches from imprinted spin-helix patterns. When spins are coupled only along two of three possible orientations (the XX model), we find ballistic behaviour of spin dynamics, whereas for isotropic interactions (the XXX model), we find diffusive behaviour. More generally, for positive anisotropies, the dynamics ranges from anomalous superdiffusion to subdiffusion. Furthermore, with anisotropic spin couplings, transverse spin components are no longer conserved and can decay not only by transport, but also by dephasing. We observe fast, local spin decay controlled by the anisotropy. Additionally, we directly observe an effective magnetic field created by superexchange which causes an inhomogeneous decay mechanism due to variations of lattice depth between chains, as well as a homogeneous dephasing mechanism due to the twofold reduction of the effective magnetic field at the edges of the chains and due to fluctuations of the effective magnetic field in the presence of mobile holes. |
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F01.00073: Emergent quantum state designs from individual many-body wavefunctions Jordan Cotler, Daniel Mark, Hsin-Yuan Huang, Felipe Hernandez, Joonhee Choi, Adam L Shaw, Manuel Endres, Soonwon Choi In this poster, we describe a universal phenomenon that occurs in strongly interacting many-body quantum dynamics, beyond the conventional notion of thermalization. Specifically, we point out that a single many-body wavefunction can encode a large ensemble of pure states defined on a subsystem. We analyze the statistical properties of the ensemble using a notion from quantum information theory called quantum state k-designs. We find that, across a wide range of examples, these ensembles are universal and highly random. First, we analytically prove that almost all many-body wavefunctions in Hilbert space encode ensembles sharing the same statistical properties, namely the formation of approximate k-designs. Second, we numerically establish that the same properties also arise from time-evolved states and from energy eigenstates of generic chaotic Hamiltonians at infinite temperature. The special case of our results at k=1 reproduces conventional thermalization. Our results offer a new approach for studying quantum chaos and provide a practical method for sampling approximately uniformly random states. The latter has wide-ranging applications in quantum information science from tomography to benchmarking, including a new benchmarking method that has been demonstrated in a Rydberg quantum simulator. |
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F01.00074: Emergent Randomness and Benchmarking from Many-Body Quantum Chaos Adam L Shaw, Joonhee Choi, Ivaylo S Madjarov, Xin Xie, Jacob P Covey, Jordan Cotler, Daniel Mark, Hsin-Yuan Huang, Anant Kale, Hannes Pichler, Fernando Brandao, Soonwon Choi, Manuel Endres In this work we find experimental signatures of random quantum state ensembles emerging from evolution with only a global, time-independent Hamiltonian, and use these ensembles to realize a new device benchmarking scheme applicable to both analog and digital quantum simulators. Specifically, we find that measurement results associated with small subsystems exhibit signatures of random state ensembles appearing after chaotic quantum many-body dynamics. This phenomenon turns out to be universal in a wide variety of quantum platforms, enabling the benchmarking of quantum device fidelity with significantly reduced experimental complexity, which we demonstrate using a Rydberg quantum simulator. |
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F01.00075: DEGENERATE GASES AND MANY-BODY PHYSICS
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F01.00076: Towards Quantum Simulation of Light-Matter Interfaces with Strontium Atoms in Optical Lattices Annie Jihyun Park, Jan Trautmann, Valentin Klüsener, Dimitry Yankelev, Dimitrios Tsevas, Yilong Yang, Immanuel F Bloch, Sebastian Blatt Quantum simulators based on ultracold atoms in optical lattices are renowned for their success in emulating strongly correlated condensed matter systems. In addition, recent theoretical proposals show that the high degree of controllability of these simulators also enables emulating strongly-coupled light-matter-interfaces in parameter regimes that are unattainable in real photonic systems. To realize these exciting proposals, the integration and development of experimental tools are necessary. Towards this goal, we have developed an in-vacuum, monolithic build-up cavities which will be used to increase the system sizes in quantum gas microscopes by an order of magnitude compared to the state-of-the-art, improve the lattice homogeneity, and enhance the lattice depth. These advantages will reduce finite size effects and allow implementing state-dependent lattices, which are a key ingredient to the aforementioned proposals. To benchmark the size and homogeneity of the lattices created in these cavities, we image their intensity profile using clock spectroscopy. Although our purpose for the cavities are focused on quantum simulation, our results present a viable solution to create ultracold atoms experiments where compactness, stability, and large, deep lattices can be achieved simultaneously. |
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F01.00077: Towards single-site imaging of an erbium quantum gas microscope Lin Su, Robin Groth, Aaron Krahn, Anne H Hebert, Furkan Ozturk, Gregory A Phelps, Markus Greiner Single-site imaging of atoms in optical lattices is a powerful way of studying quantum systems. We present updates on an erbium quantum gas microscope, which features a high-resolution imaging system, a low-disorder optical lattice, and an accordion lattice with tunable spacing. High-resolution imaging is realized via a custom, in-vacuum objective (numerical aperture = 0.9) with diffraction-limited performance across a large field of view. To minimize disorder in the lattice potential, the objective features a hole along the optical axis so that a beam can go through the objective and then be retro-reflected from a mirror many Rayleigh lengths away from the atoms. The accordion lattice, projected through the objective, features galvanometers and interferometrically aligned beam splitter prisms to manipulate the lattice spacing from 266 nm to more than 5 um. Such tunability helps to increase imaging fidelity, allows for spin-resolved imaging of many spin states in a single shot, and may also be used to study the cooperative resonances of two-dimensional atom arrays in quantum optics and optomechanics. Overall, these features make the experiment an ideal platform for next-generation quantum gas microscopy and pave the way for quantum simulation of ultracold atoms in optical lattices with long-range interactions. |
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F01.00078: Excited State Quantum Phase Transition, Generalized Kibble-Zurek Mechanism, Eigenstate Duality, and Spectrum Structure Duality Tie-Cheng Guo, Li You Universality and duality are two important concepts in physics. We point out two intriguing dualities for a variety of quantum many-body systems: the eigenstate duality and the spectrum structure duality, with the former between systems of opposite interactions and the latter uncovering an exotic hidden symmetry. Universality class is often discussed in the context of quantum phase transition (QPT) and adiabatic driving dynamics. First, we investigate Excited State Quantum Phase Transition (ESQPT) characterized by a divergent Density of States (DOS) with respect to the energy and parameter variables. This leads to the introduction of two other types of ESQPTs. In the celebrated ground state Kibble-Zurek mechanism (KZM) crossing a second order or continuous phase transition, when the initial ground state is slowly ramped through the continuous QPT critical point, excitations/defects exhibit a power law scaling with respect to the total ramping time τ in the adiabatic limit τ →∞ . We generalize the KZM physics to systems with first-order QPT critical point and find that when the initial state is slowly ramped through a first-order QPT critical point, excitations/defects generated during the slowly driven dynamics also exhibit a power law universal scaling. We further consider the excited state KZ (ESKZ) scenario. For an initial excited eigenstate, the system can be analogously driven slowly through an ESQPT critical point. Excitations/defects generated in the ESKZ scenario can be described by an ESKZM we propose, which predicts also a universal power law scaling in the adiabatic limit τ →∞ . All the cases considered above can be called and described by the generalized KZM (gKZM) which governs the universal behavior for excitations/defects whenever adiabatic dynamics acrossing a QPT critical point happens in a quantum many-body system. We illustrate the related general concepts and mechanism in the model system of a spin-1 atomic Bose-Einstein condensate (BEC). |
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F01.00079: High Resolution Imaging and Control of Quantum Degenerate $^{133}$Cs-$^6$Li Bose-Fermi Mixtures Geyue Cai, Krutik Patel, Cheng Chin We present progress on the investigation of Bose-Einstein condensates of $^{133}$Cs atoms immersed in degenerate Fermi gases of $^{6}$Li atoms. Deep in quantum degeneracy, fermion excitations near the Fermi surface can induce effective interactions between condensed bosons. The strength and sign of this mediated interaction is predicted to oscillate at a length scale given by the Fermi wavelength, which is about 1$\mu$m in our system. We develop a high resolution microscope and a digital micro-mirror device to image and manipulate the degenerate quantum mixtures at a length scale close to the Fermi wavelength. The upgraded system permits new schemes to characterize the long range nature of the fermion-mediated interactions between bosons, and offers a versatile platform to study novel quantum phases and dynamics of interacting Bose-Fermi mixtures. |
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F01.00080: Topological Materials of Light in Degenerate Multimode Cavities Claire Baum, Lukas Palm, Matthew Jaffe, Logan W Clark, Nathan A Schine, Ningyuan Jia, Jon Simon Topologically ordered materials can be explored via cavity Rydberg polaritons, quasiparticles composed of part cavity photon and part atomic Rydberg excitation. The Rydberg component facilitates strong interactions between polaritons, while the cavity component allows us to shape the polariton energy landscape via the mode structure of a twisted optical cavity. Enabled by these concepts, we recently prepared the first two-particle Laughlin state of light. We now describe our efforts to prepare larger, topologically-ordered states through a newly designed highly degenerate multimode cavity and dissipative state preparation. |
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F01.00081: A Modern Control and Sequencing Platform for Quantum Gas Experiments Nicholas E Kowalski, Nathan Fredman, Joshua Zirbel, Brian L DeMarco We present a new sequencing and control platform for use with ultracold gas experiments, developed by Entangleware and piloted/co-developed by the DeMarco Research group. The system is built around a FPGA core that provides 128 independent digital signals with 20ns timing, using industry-standard hardware from National Instruments. The FPGA core is married to NI analog signal sources based on PCI-cards, providing the full range of digital and analog signals needed to control the experiment. The primary user-interface is in the Python programming language. The intermediate-level Entangleware program converts the Python into machine code and interacts with the hardware drivers. We are developing Python libraries for other useful devices, such as DDS frequency sources that can be purchased as low-cost evaluation boards, and will make them available in an open-source repository. |
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F01.00082: Preparing a Superfluid in a Bose Hubbard lattice Gabrielle Roberts, Brendan Saxberg, Andrei Vrajitoarea, Margaret G Panetta, Ruichao Ma, David I Schuster, Jon Simon Synthetic photonic systems provide a promising platform for exploring the physics of highly correlated quantum materials. Using the flexible toolset of microwave photons and superconducting circuits in the circuit QED paradigm, we build a 1D Bose-Hubbard lattice where capacitively coupled transmon qubits serve as lattice sites, and the transmon anharmonicity produces strong photon-photon collisions. Individual readout resonators allow site-, time-, and occupancy- resolved microscopy of the photonic lattice. In previous work, we employed an engineered reservoir to realize a dissipatively stabilized site and coupled it to the lattice to prepare a n=1 Mott insulating phase of light. Recent improvements to our apparatus enable us to locally probe multi-site correlations and thus precisely characterize delocalized lattice states. We discuss prospects for melting our prepared Mott insulator into a superfluid by adiabatically tuning the volume of our chain, and investigating correlations during both the cooling and the steady state.These efforts can shed light on the intricate interplay of entanglement and thermalization in these QMB systems. |
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F01.00083: Quantum impurity ultrastrongly coupled to a photonic crystal waveguide Andrei Vrajitoarea, Ron Belyansky, Rex O Lundgren, Seth P Whitsitt, Alexey V Gorshkov, Andrew Houck Superconducting circuits have emerged as a rich platform for emulating synthetic quantum materials composed of artificial atoms and photonic lattices. In this work, we apply this toolbox for exploring the physics of a quantum impurity coupled to the many discrete modes of a photonic crystal lattice. In previous work, strongly coupling a transmon qubit to the band structure of a stepped impedance waveguide has led to the first observation of atom-photon dressed bound states. In this experiment, the light-matter coupling strength is pushed into the ultrastrong coupling regime, where the qubit is simultaneously hybridized with many modes and the total number of excitations is not conserved. Our platform consists of a fluxonium qubit galvanically coupled to a linear chain of coupled microwave resonators. Probing transport through the waveguide reveals that the propagation of a single photon becomes a many-body problem as multi-photon bound states participate in the scattering dynamics. Furthermore, we study the effective photon-photon interactions induced by the impurity by probing the inelastic scattering spectrum. Signatures of multi-mode entanglement are inferred from measuring correlations in the emitted quadrature fields at each waveguide mode. Our results highlight a single nonlinear impurity ultrastrongly coupled to a discrete photonic bath as a novel platform for studying many-body physics with interacting photons and generating multi-mode entanglement. |
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F01.00084: Strongly Interacting Mixtures of 23-Na and 40-K Eric Wolf, Yiqi Ni, Alexander Chuang, Carsten Robens, Martin W Zwierlein Mixtures of quantum fluids lie at the forefront of research into strongly-correlated quantum matter. We explore the rich phase diagram of the Bose-Fermi mixture in the impurity limit by immersing fermionic impurities in a Bose-Einstein condensate (BEC) with near-resonant interactions. We create Bose polarons near quantum criticality and probe their energy, spectral width, and short-range correlations as a function of temperature. We observe their inverse lifetime, determined via spectral width, to increase linearly with temperature at the Planckian scale, a hallmark of quantum critical behavior. |
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F01.00085: Progress on creating Bose--Einstein condensate bubbles in low-earth orbit using Science Module 3 (SM3) of the Cold Atom Laboratory (CAL) Joseph D Murphree, Nathan Lundblad, David Aveline, Courtney Lannert, Brendan Rhyno, Smitha VIshveshwara A Bose–Einstein condensate confined to the surface of a thin shell is predicted to exhibit novel properties due in part to its topology, including modified collective modes and vortex dynamics. Although shell potentials have been created using static magnetic fields dressed by radio-frequency radiation, experimental realization of these bubbles is hampered by Earth's gravitational field, which pools the atoms earthward. The Cold Atom Laboratory (CAL) aboard the International Space Station (ISS) offers a particularly elegant solution by allowing the experiments to be conducted on its user facility in the microgravity environment of low earth orbit. We report on progress in creating ultracold bubbles in rf-dressed traps using the most recent CAL apparatus, Science Module 3 (SM3), taking advantage of its capabilities of dual-axis imaging, Stern-Gerlach techniques, and Bragg spectroscopy. |
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F01.00086: G-wave pairing and density-dependent gauge field in a Bose-Einstein condensate Shu Nagata, Zhendong Zhang, Kai-Xuan Yao, Liangchao Chen, Cheng Chin In our first work, we report the observation of BECs of spinning Cs2 molecules by inducing pairing interactions in an atomic condensate near a g−wave Feshbach resonance in a two-dimensional, flat-bottomed trap. A large suppression of collision loss of the molecules due to the low temperature and trap geometry permits thermal equilibrium. From our measurement of the equation of state, we determine the molecular scattering length to be +220(30) Bohr. We also investigate the unpairing dynamics within the molecular condensate near the resonance and confirm the dynamics are consistent with the unitarity limit. Our work confirms the transition between atomic and molecular condensate, the bosonic analog of the BEC-BCS (Bardeen-Cooper-Schrieffer superfluid) crossover in a Fermi gas. In our second work, we investigate the equilibrium and dynamical properties of a BEC with a density-dependent gauge field. Using Floquet engineering, we create a gauge field that takes one of two values depending on the density. Atoms condensed at different momenta form domains, separated by domain walls. Our scheme allows for a large change of the gauge field over a small range of the density. Furthermore, the low loss and heating of this scheme allows us to investigate the equilibrium and dynamics of the system over hundreds of milliseconds. We observe formation of domains and study the dynamics of the domain wall in response to a time dependent gauge field. |
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F01.00087: Efficient production of Bose-Einstein Condensates of168Er Mingchen Huang, Bojeong Seo, Ziting Chen, Mithilesh Parit, Peng Chen, Gyu-boong Jo Lanthanide atoms such as dysprosium and erbium have attracted significant attention in quantum simulation with ultracold atoms due to their large magnetic moment and richness of Feshbach resonances. In this poster, we will demonstrate the production of Bose-Einstein Condensates of 168Er atoms in a new apparatus. By using the technique of two-stage slowing, we improve the loading efficiency into the magneto-optical trap (MOT) and operate a narrow-line MOT , followed by the forced evaporative cooling in a crossed optical dipole trap. The efficient production of ultracold Er atoms allows us to explore unprecedented quantum phenomena with dipolar interactions. We will also discuss our recent experimental progress. |
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F01.00088: Exploring quantum dynamics with ultracold lithium in optical lattices Jeremy Tanlimco, Ethan Q Simmons, Roshan Sajjad, Alec J Cao, Eber Nolasco-Martinez, Toshihiko Shimasaki, Hasan E Kondakci, Hector Mas, David M Weld Ultracold lithium atoms in periodically modulated optical lattices serve as an ideal experimental platform for probing the dynamics of driven quantum systems. We report recent progress on several experiments along these lines, including Poincaré phase-space portraits of transport in driven inhomogeneous lattice gases and many-body prethermalization and delocalization in an interacting quantum kicked rotor. We describe future prospects for investigation of time-domain condensed matter physics, event-horizon dynamics of atoms with relativistic dispersion in a driven optical cavity, and quantum heat engines. |
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F01.00089: 3D Numerical Simulations of BEC Transport Using Shortcuts to Adiabaticity Christopher J Larson, Skyler Wright, Edward Carlo C Samson We report on our numerical simulations of high-fidelity, fast quantum control of Bose-Einstein condensates (BECs) as we extend them to full 3D simulations. We simulate a 3D painted potential that provides complete confinement of the atoms. Painted potentials also allow for arbitrary and dynamic traps, which control the spatial transport of the BEC. To maintain high fidelity after transport, we implement shortcuts-to-adiabaticity (STAs) to design the BEC trajectory in our simulations. STAs allow fast movement while suppressing excitations that can result due to the rapid transitions of the quantum state. In our 3D simulations, quantum fidelities resulting from different, experimentally viable transport times and trap-depths are compared. |
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F01.00090: Explorations in localization, compact atom sources and anyons with ultracold strontium Max Prichard, Toshihiko Shimasaki, Peter Dotti, Jared E Pagett, Enrique Morell, Esat Kondakci, David M Weld Ultracold atoms in bichromatic lattices serve as an ideal experimental platform for implementing the Aubry-André model and extensions thereof. We present recent work exploring the intersection of dynamical and disorder-induced localization in a Kicked Aubry-André model, as well as results demonstrating phasonic spectroscopy of Strontium in a bichromatic optical lattice. Separately, we describe a second-generation compact atom source experiment in which a magneto-optical trap of strontium is loaded by laser illumination of strontium oxide, as well as progress on efforts to realize non-Abelian anyons in a biased zig-zag lattice. |
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F01.00091: COLD ATOMS, IONS, MOLECULES, AND PLASMAS
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F01.00092: Spectral properties of a three-body atom-ion hybrid system Daniel J Bosworth, Maxim Pyzh, Peter Schmelcher We consider a hybrid atom-ion system consisting of a pair of bosons interacting with a single ion in a quasi-one-dimensional trapping geometry. Building upon a model potential for the atom-ion interaction developed in earlier theoretical works, we investigate the behaviour of the low-energy eigenstates for varying contact interaction strength g among the atoms. In particular, we contrast the two cases of a static ion and a mobile ion. Our study is carried out by means of the Multi-Layer Multi-Configuration Time-Dependent Hartree method for Bosons, a numerically-exact ab initio method for the efficient simulation of entangled mixtures. We find that repulsive atom interactions induce locally-distinct modifications of the atomic probability distribution unique to each eigenstate. While the atoms on average separate from each other with increasing g, they do not necessarily separate from the ion. The mobility of the ion leads in general to greater separations among the atoms as well as between the atoms and the ion. Notably, we observe an exchange between the kinetic energy of the atoms and the atom-ion interaction energy for all eigenstates, which is both interaction- and mobility-induced. For the ground state, we provide an intuitive description by constructing an effective Hamiltonian for each species, which aptly captures the response of the atoms to the ion's mobility. Furthermore, the effective picture predicts enhanced localisation of the ion, in agreement with our results from exact numerical simulations. |
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F01.00093: Circular Rydberg states for quantum many-body physics Christian Hölzl, Muamera Basic, Aaron Götzelmann, Florian Meinert Highly excited low-l Rydberg atoms in configurable mircotrap arrays have recently proven highly versatile for studying quantum many-body systems with single particle control. I will report on the advances of a new project pursuing to harness high-l circular Rydberg atoms for quantum simulation. When stabilized against spontaneous and blackbody radiation induced decay in a suitable cavity structure, circular Rydberg states promise orders of magnitude longer lifetimes compared to their low-l counterparts and thus provide an appealing potential to strongly boost coherence times in Rydberg-based interacting atom arrays. To maintain excellent high-NA optical access we employ a capacitor made from indium tin oxide (ITO) thin films [1], which combines transparency in the visible spectral range with high reflection of microwaves. With this approach, we aim to realize long lifetimes for circular Rydberg states even at room temperature. |
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F01.00094: Spectroscopy of a narrow cooling transition in Holmium Christopher Yip, Mark Saffman We report on accurate measurements of the hyperfine constants of the narrow cooling transition of neutral Holmium at 412.1 nm. This transition has a linewidth of 2.3 MHz and a Doppler temperature of 55 microK which renders it suitable for second stage laser cooling. The proximity of the wavelength to the strong cooling transition at 410.5 nm[1] renders this transition convenient for first and second stage cooling using a combined optical setup. The hyperfine constants were measured using Doppler free saturated absorption spectroscopy in a hollow cathode discharge. Relative measurements of the locations of the hyperfine levels were made using an EOM modulator with an RF offset relative to a stable ULE cavity reference. The A and B hyperfine constants were determined to be A= 715.85±0.15 MHz and B= 1013±16.0 MHz which significantly improves on the precision of earlier measurements. |
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F01.00095: Vacuum-induced collective dynamics in three-level V-type atomic systems Ahreum Lee, Hyok S Han, Kanupriya Sinha, Fredrik Fatemi, Steven L Rolston The phenomenon of spontaneous radiation refers to the decay of an excited atom via interaction with the vacuum electromagnetic (EM) field. When there are many atoms interacting coherently with a common vacuum EM field, the collective atom-field interaction can lead to the atomic ensemble decaying with an enhanced or suppressed rate [1]. We extend the theory to an ensemble of multiple three-level V-type atoms that allows for quantum beats. We analytically solve the collective atomic dynamics following the sudden turn-off of a weak drive field resonant with one excited state, assuming all atoms to be localized within a sub-wavelength region. Interference between two different transitions, as well as among multiple atoms, manifests as collective quantum beat dynamics in subsequent emission. Surprisingly, collective quantum beats appear even when the atomic ensemble starts from only one excited level as the vacuum field provides required coherence through second-order coupling to the other excited level. Our calculated field intensity with no initial superposition matches well with experiment [2], where we detect absorption in the forward direction where the phases add constructively, providing superradiance and enhanced quantum beat amplitudes. Our work is the first demonstration of quantum beats without initial superposition due to vacuum-induced coupling of excited levels and shows fascinating interplay between multi-level and multi-atom features. |
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F01.00096: Light-assisted collisions and time-of-flight experiments in optical tweezers Mark O Brown, Cindy A Regal, Jose P D'Incao, Tobias S Thiele, Willa Dworschack Single neutral atoms trapped in tightly-confining optical tweezers form a powerful system for studying quantum computation and quantum simulation. Here, we present research on preparing and characterizing controlled states of number and motion of atoms in these tweezers. We are using free-space imaging and our control over tunnel couplings in order to characterize atomic motion. We also present calculations of the molecular dynamics of atoms undergoing light-assisted collisions, which are important for loading optical tweezers with single atoms. We discuss how these collisions that happen at relatively long-range distances and low energy scales pose unique challenges and can be elucidated in the controlled environment of optical tweezers. |
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F01.00097: Laser Cooling of CaOH and CaOCH3: Optical Cycling and Branching Ratios Christian Hallas, Nathaniel Vilas, Loic Anderegg, Benjamin Augenbraun, Louis Baum, Debayan Mitra, John M Doyle Polyatomic molecules possess several unique features that have no direct analogues in atoms and can open new scientific possibilities in quantum simulation, ultracold chemistry, and precision measurements. Recent progress in laser cooling has brought several diatomic species into the ultracold regime via magneto-optical trapping (MOT) and sub-Doppler cooling. Here, we report on progress to extend these techniques to polyatomic molecules. Following our work creating a 1D MOT for CaOH, we now report white-light radiative slowing of a beam of CaOH, enabled by realizing a highly closed optical cycling scheme. Similarly, following our work on Sisyphus laser cooling of the symmetric top molecule CaOCH3, we present progress towards radiative slowing and trapping of that species, and discuss the possibility of creating optical tweezer arrays of these and other, more complex, molecules. |
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F01.00098: Utilization of ISS Destiny Lab and Astronauts for Installation and Complex Upgrade of the Cold Atom Lab Instrument James Kellogg, Ethan Elliott, David Aveline, Jim Kohel, Kamal Oudrhiri, Robert Thompson Cold Atom Lab (CAL) is a miniaturized multi-user quantum physics laboratory that utilizes ISS for microgravity based cold atom fundamental science experiments. The CAL instrument was installed on orbit by astronauts in May 2018, and then almost two years later was upgraded to replace the heart of the instrument known as the Science Module with an upgraded version that added atom interferometry capabilities. |
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F01.00099: Detachable 2D MOT platform as a source of cold cesium atoms Jonathan Yang, Kaiyue Wang, Colin V Parker, Eric Mulero-Flores, Matthew Dittrich The basis of many experiments in atomic physics starts with the production of a sample of trapped cold atoms using a magneto-optical trap (MOT). We load a MOT in our 3D test chamber from a continuous collimated beam of cold cesium (Cs) atoms produced by a detachable 2D MOT platform. This detachable 2D platform is designed such that a single laser source is split five ways with each beam being reflected into both the horizontal and vertical directions with the polarizations being accounted for. After the MOT loading the magnetic field gradient and frequency detuning is then increased in which the Cs atoms enters a compressed MOT (CMOT) stage. The atoms are subsequently cooled through an optical molasses, where the detuning is further extended, the magnetic field gradient is removed and the residual field is minimized through the aid of compensation coils, one for each MOT beam direction. After the optical molasses stage the detuning is ramped back and we take absorption images to measure the temperature and the atomic density through the time-of-flight method. |
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F01.00100: Progress on continuous-wave Lyman-α laser for cooling hydrogen Tharon D Morrison, Nathaniel D McDonough, Gerald Gabrielse Precision spectroscopy of hydrogen allows probes into the proton size, fundamental constants, and matter-antimatter symmetry. Laser cooling of hydrogen beams will provide reductions in the most prominent systematic broadening and shifting mechanisms to these transitions. We report progress on a CW Lyman-α source projected to reach 1 μW of VUV and on simulations of laser cooling hydrogen based on this projected power. |
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F01.00101: High density and loading rate MOT of K atoms using a buffer-gas beam source Maryam M Hiradfar, Zack Lasner, Debayan Mitra, Sridhar Prabhu, Lawrence W Cheuk, Benjamin Augenbraun, Eunice Lee, John M Doyle Whereas AMO experiments with alkali atoms typically rely on dispenser- or oven-based sources of gas-phase atoms, cold radical molecules are more commonly generated from a cryogenic buffer gas beam (CBGB). Building on previous proof-of-principle work that demonstrated efficient loading of lanthanide-series atoms into a magneto-optical trap (MOT), we achieve an exceptionally dense MOT of potassium atoms using the D2 line, with a loading time of only $\sim$10 ms. This method could be applied to any cold atom experiment, and would be especially useful when very high initial atomic MOT densities or $ll$100 ms loading times are required. Explorations of high repetition rates will also be discussed. |
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F01.00102: Towards trapping of single neutral atoms in 3D-printed optical tweezers Sina Hammer, Paul Ruchka, Ralf Albrecht, Marian Rockenhäuser, Simon Thiele, Harald Giessen, Tim Langen Trapping of single ultracold atoms is an important tool for applications ranging from quantum computation and communication to sensing. However, one of the main disadvantages of most experimental setups is their large size and high level of complexity. Here we report on the progress towards integrating a 3D printed optical tweezer with a rubidium magneto-optical trap. The tweezer is formed by micrometer scale lenses that are fabricated directly onto the tip of a standard optical fiber. Its unique properties will make it possible to both trap single atoms and collect their fluorescence with high efficiency. Based on this, a single photon source can be realized that will have versatile applications in quantum information processing. |
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F01.00103: Doppler-free spectroscopy of launched laser-cooled atoms, in preparation for Rydberg excitation Da Thi Hoang, Jeffrey S Dunham, Anne Goodsell We investigate Doppler-free spectroscopy of cold 85Rb atoms launched from a magneto-optical trap (MOT). Each cold-atom cloud travels upward with vertical speed vy = 5.9±0.4 m/s and transverse speed vx = 0.4±0.1 m/s, passing through a near-resonant probe beam. We observe three spectral features corresponding to the D2 manifold of 85Rb with minimal Doppler broadening. The prominent feature for F = 3 → F' = 4 yields transmission T = 0.94. For comparison, we build on a pre-existing model of absorption in warm atoms to predict the spectrum of cold atoms transitioning from the 5S1/2 state to the 5P3/2 state. These results confirm and add to current understanding of cold atom absorption of near-resonant laser light in real experimental conditions, laying the groundwork for further exciting experiments such as multi-photon absorption to reach selected sublevels of the Rydberg state with n = 35. |
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F01.00104: Automating the Tuning of Magneto-Optical Trap Lasers for Use in Neutral Atom Quantum Computing Jacob Mandel, Jonathan Flores, Michael Pilgrim, Andrew Jarymowycz, Katharina Gillen Neutral atom quantum computers use atoms trapped by light as quantum bits. Our group focuses on computationally exploring light patterns useful for quantum computing [1-3] and investigating their properties experimentally. To hold atoms in light patterns, they must first be cooled to sub-mK temperatures using a magneto-optical trap (MOT). The MOT requires two lasers (trap and repump) tuned to the correct hyperfine transitions of the atom to within 1:100,000,000. |
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F01.00105: Towards Programmable Strontium Atom Arrays Aaron Holman, Weijun Yuan, Max Aalto, Quan Gan, Minho Kwon, Sebastian Will We report on progress towards the realization of programmable strontium atom arrays. We present the design of our apparatus, including a novel 2D magneto-optical trap for strontium and our approach to generating versatile atomic arrays. Our system is designed as an optical tweezer platform, in which atoms can be trapped at close proximity to each other. We will utilize holographic metasurfaces, in tandem with magic trapping light in the green, that enables the positioning of atoms at sub-micron distances in nearly arbitrary trapping geometries. At close spacings, the dissipation dynamics of atoms is predicted to be significantly altered by collective atom-photon interactions. We plan to exploit such collective effects to create highly entangled many-body quantum states that display subradiance, boosting the atomic coherence time beyond their natural lifetime. In addition to fundamental quantum optics experiments, our platform will lend itself for applications in quantum simulation and quantum computing. |
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F01.00106: Progress towards chip-scale transverse laser cooling of thermal atomic beams Chao Li, Benoit Hamelin, Farrokh Ayazi, Chandra Raman We present progress toward on-chip laser cooling of thermal rubidium atomic beams in an integrated platform using microfabricated collimators and MEMS mirrors. An array of etched thin silicon microcapillaries are attached to a rubidium reservoir containing a dispenser source. The photolithographically patterned array collimates and directs thermal atoms to the downstream cooling region with pinpoint accuracy. Micromirrors at the cooling region maneuver laser beams to form a strong standing wave, a stimulated blue molasses, that can reduce the transverse velocity spread to the cm/s range within a sub-centimeter travel distance. We have fabricated collimators and micromirrors, and performed stringent tests of the resistance of the latter to alkali deposition by directly spraying rubidium atoms emitted from dispensers. Our study shows that a dielectric coating layer effectively protects the gold mirrors from alkali attack compared with non-coated mirrors, as revealed by scanning electron micrograph (SEM) inspections on the test samples. The robustness of our micromirrors embedded with the beam source guarantees its reliability for long-term operation. This on-chip hybrid of passive and active collimation paves the way towards a high-brightness atomic beam source that can find its applications in making compact atomic instruments. |
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F01.00107: Additively manufactured performance-optimized components for quantum technologies and beyond Somaya H Madkhaly, Nathan Cooper, Lucia Hackermueller Magneto-optical traps (MOT) are the starting points of many quantum technology systems and all cold atom experiments, such as atomic clocks, sensors, precision measurements, BEC experiments, and more. These extremely precise systems are often large and heavy, expensive, hard to operate by non-experts, frequent maintenance demanding, and are difficult to operate outside of laboratories due to their sensitivity to environmental conditions. Transferring these experiments to real-life applications requires the development of robust, lightweight, and affordable experimental components. We demonstrate the use of novel additive manufacturing (AM) techniques to produce portable, small, lightweight, and inexpensive modules for cold atom systems. We employ a compact and stable device for spectroscopy and optical power distribution, optimized neodymium magnetic rings for magnetic field generation, and a lightweight additively manufactured ultra-high vacuum chamber [1] to create a magneto-optical trap that captures ~2×108 85Rb atoms. Our chamber weighs less than 30% of a standard chamber, and our optical setup is only ~5% the volume of typical setups. Our experimental test results demonstrate that our AM-manufactured system is resistant to extreme environmental changes and as efficient and functional as conventional lab-based devices. We believe that our novel approach is a new standard that will be a basis for numerous applications in quantum technology areas and fundamental research. [1] Cooper, N., Coles, L. A., Everton, S., Maskery, I., Campion, R. P., Madkhaly, S., ... & Hackermüller, L. (2021). Additively manufactured ultra-high vacuum chamber for portable quantum technologies. Additive Manufacturing, 101898. |
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F01.00108: Quantum and classical simulations of parametric heating in gaussian potential wells Hansen Wu, Pei Robins, Jeffrey A Collett Optical dipole traps hold cold atoms in potential energy wells that are approximately quadratic at low energies but more closely approximated as gaussian at higher energies. Parametric heating is commonly used to eject atoms from dipole traps as a diagnostic for the low amplitude resonant frequency of oscillation in the trap. A gaussian trap with a depth of about 1000 times the low amplitude quantum of exictation was simulated quantum mechanically by finding the lowest 1500 states in the static gaussian well and then solving the time dependent Schrodinger equation with a parametric perturbation. Classical and quantum simulations of the heating process were compared and showed that a classical simulation does not match the quantum result for atoms deep in the trap but that it works much better as the particle energy increases as one would expect based on the Bohr correspondence principle. Both simulations show that a down-chirped pulse with a frequency variation of about 20 percent is effective at ejecting particles from the trap. We conclude that classical simulations are adequate for finding strategies for ejecting atoms, but that they do not model low energy dynamics well. |
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F01.00109: Lattice confined mixtures and molecules of Yb and Li: Feshbach resonances and interaction-driven dynamical delocalization Xinxin Tang, Jun Hui See Toh, Katherine C McCormick, Subhadeep Gupta We will report on experiments on ultracold ytterbium and lithium atoms in lattice confinement. After having observed multiple interspecies magnetic Feshbach resonances between the open-shell Li and the closed-shell Yb ground state atoms [1], we are working to apply these resonances towards the magnetoassociation of ultracold YbLi molecules in the electronic ground state. Magnetoassociation efficiency can be enhanced in an optical lattice geometry to provide high spatial overlap between the species. We will report on our successful implementation of a three-dimensional optical lattice at the optical wavelength of 1073nm for the two-species mixture. Using two arms of the lattice to create 1D traps, and the third as a pulsed-standing-wave source, we have also realized a quantum kicked rotor in 1D. We will additionally report on our observation of interaction-driven dynamical delocalization using Yb bosons in this system. |
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F01.00110: Observation of bidirectional and unidirectional ratcheting in a dissipative optical lattice Ian T Dilyard, Kefeng Jiang, Alexander Staron, Samir Bali We confine cold atoms in a 3D tetrahedral lin-perp-lin dissipative optical lattice and illuminate these atoms, which are diffusing in all directions, with a weak probe beam propagating along a lattice axis. Probe-induced directed propagation is observed along a lattice axis perpendicular to the probe beam, in both positive and negative directions symmetrically, thus yielding a bidirectional ratchet. The experimental signature for bidirectional ratcheting manifests as ``Brillouin"-like resonances in the probe transmission spectrum. By angling the probe beam off-axis, we show that the atoms now preferentially propagate in either the positive or the negative direction, thus yielding a unidirectional ratchet. The experimental signature for unidirectional ratcheting is revealed as a splitting of the Brillouin resonance into a central feature corresponding to the vibrational frequency for a non-propagating atom oscillating inside a well, flanked by two side-features one of which corresponds to directed motion along the positive direction and the other along the negative direction. By analyzing pump-probe spectra with an angled probe beam, we show, with good theoretical agreement and greater resolution than before, how the split-Brillouin resonances shift with probe angle. |
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F01.00111: Exploring interacting bosons in an artificial gauge field Perrin C Segura, Sooshin Kim, Joyce Kwan, Robert Schittko, Julian Leonard, Markus Greiner We engineer and investigate strongly correlated many-body states using ultra-cold Rb atoms in an optical lattice. This clean, highly controlled system offers an opportunity to study microscopic quantities of strongly correlated states that are difficult to access in experiments that rely on measurements of a system's bulk properties. Current work is focused on investigating states associated with interactions between bosons in the presence of a magnetic field. To accomplish this, we use a technique based on laser assisted tunneling to implement an artificial gauge field. We construct arbitrary potential landscapes, which enables state preparation by adiabatically transforming the system from a topologically trivial ground state into the strongly correlated target state. We are also able to capture images with single-site resolution. These images provide direct measurements of many-body correlation functions, which are used to reveal insight into the thermodynamic proprieties of the system. |
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F01.00112: Novel platforms for quantum simulation using a lithium-6 quantum gas microscope: tweezer arrays and Rydberg-dressed fermions Zoe Yan, Benjamin M Spar, Elmer Guardado-Sanchez, Waseem S Bakr Over the past few years, fermionic quantum gas microscopes have been used to explore equilibrium and dynamical properties of the Fermi-Hubbard model. We describe two methods by which we are expanding the simulation capabilities of this platform to study the effects of non-local interactions and to create low-entropy many-body states. First, we achieve strong non-local interactions by off-resonantly coupling our neutral atoms to a highly excited Rydberg state via a single-photon transition, a technique known as Rydberg dressing. Our system realizes a spinless fermion t-V model. We find that strong nearest-neighbor interactions in this system slow down the relaxation dynamics of imprinted charge density waves. Second, we reach record low entropies with a one-dimensional lattice system formed by optical tweezers. We adiabatically prepare a low entropy correlated state at half filling in an 8 site lattice. By generating tweezers with multiple acousto-optical modulators or a spatial light modulator, we can expand this system to a two-dimensional array with hundreds of atoms in the future. In addition to studying lower temperature Fermi-Hubbard physics, with this platform we will be able to study Hamiltonians with flexible geometries and single site control while being compatible with our already demonstrated Rydberg dressing capabilities. |
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F01.00113: Direct Characterization of Dirac Points in an Optical Honeycomb Lattice Charles Brown, Shao-Wen Chang, Malte Nils Schwarz, Tsz-Him Leung, Dan M Stamper-Kurn We study properties of singularities in the band structure of a honeycomb lattice by probing the singular points directly with a BEC in an optical lattice. In a periodic system, if the band structure becomes degenerate at some quasimomentum, that point is called singular if there are no choice of gauge such that the Bloch wave function is continuous there. These singularities reveal important topological properties of the band structure, quantified by the Berry connection. In the past, the Dirac points of a honeycomb lattice have been studied by, for example, accelerating a BEC in the momentum space and enclosing the singularity in the resulting path. Here we study the singularities by directly accelerating a BEC to the singular point and making a turn with varying angle in the momentum space. Our initial results show that the population transfer after such a trajectory is close to the value predicted by a noninteracting band theory. Moreover, for a specific final quasimomentum, the population transfer is significantly less dependent on the rate we accelerate the atoms when we go past the singularity, compared to a straight path that avoids the singularity. This indicates that the transfer observed at Dirac point is mainly determined by the band topology instead of dynamics. |
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F01.00114: Observation of Microwave Shielding of Ultracold Molecules Sean Burchesky, Loic Anderegg, Yicheng Bao, Scarlett Yu, Tijs Karman, Eunmi Chae, Kang-Kuen Ni, Wolfgang Ketterle, John M Doyle Ultracold gases of high-density polar molecules have been observed to suffer rapid 2-body losses due to a variety of inelastic mechanisms ranging from chemical reactions to trap-light induced losses. Gaining control over collisional properties is a necessary step towards evaporative cooling of polar molecules. Here we demonstrate the suppression of inelastic collisional loss between two calcium monofluoride (CaF) molecules in a merged optical tweezer trap. High power circular polarized microwaves are used to engineer a repulsive interaction in 3D (i.e. for all collision trajectories). This effective repulsive shield suppresses the inelastic loss rate by a factor of six, in agreement with coupled channel calculations, which also predict an increased elastic cross section. The demonstrated microwave shielding shows a possible route to the creation of long-lived, dense samples of ultracold molecules through evaporative cooling. |
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F01.00115: Cold and ultracold reactive collisions of Li with LiNa Brian K Kendrick The results of full-dimensional and numerically exact quantum reactive scattering calculations are presented for the Li + LiNa(v=0, j=0) → Li2(v',j') + Na reaction. The calculations are based on an ab initio potential energy surface that includes an accurate treatment of the long-range dispersion interactions. Total and rotationally resolved rate coefficients are reported as a function of collision energy from 1 nK to 1 K. All contributing partial waves are included in the calculations at all energies. Several shape resonances (bumps) are observed in both the total and rotationally resolved rate coefficients within the cold energy regime. Of particular interest, the angular distributions of the scattered product states are also reported. The angular distributions exhibit significant quantum interference and resonance effects that lead to intriguing structure (i.e., spikes, ridges, bumps, and valleys) as a function of both collision energy and scattering angle. This structure is unique to each Li2 product state and could be controlled and manipulated experimentally via the selection of a particular initial LiNa rovibrational state, stereodynamics, or external fields. |
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F01.00116: Efimov Scenario for Overlapping Narrow Feshbach Resonances Yaakov Yudkin, Lev Khaykovich While Efimov physics in ultracold atoms is usually modeled with an isolated Feshbach resonance many real world resonances appear in close vicinity to each other and are therefore overlapping. Here we derive a realistic model based on the mutual coupling of an open channel and two closed molecular channels while neglecting short-range physics as permitted by the narrow character of the considered resonances. The model is applied to three distinct scenarios with experimental relevance. We show that the effect of overlapping resonances is manifested most strongly at a narrow resonance in whose vicinity there is a slightly broader one. In this system the Efimov features are pushed to lower binding energies and smaller scattering lengths by a significant factor facilitating their experimental investigation. We also analyze the rich excitation spectrum of the system and construct its phase diagram. |
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F01.00117: Spin-rotation coupling in p-wave Feshbach resonances Manuel Gerken, Binh Tran, Eleonora Lippi, Bing Zhu, Stefan Häfner, Juris Ulmanis, Eberhard Tiemann, Matthias Weidemuller We report on the observation of spin-rotation coupling in p-wave Feshbachnresonances in an ultracold mixture of fermionic 6Li and bosonic 133Cs. In addition to the doublet structure in the Feshbach spectrum due to spin-spin interaction, we observe a triplet structure of different ??ℓ states by magnetic field dependent atom-loss spectroscopy. Here, the ??ℓ states are projections of the pair-rotation angular momentum ℓ on the external magnetic field. Through comparison with coupled-channel calculations, we attribute the observed splitting of the ??ℓ = ±1 components to electron spin-rotation coupling. Comparison with an oversimplified model, estimating the spin-rotation coupling by describing the weakly bound close channel molecular state with the perturbative multipole expansion, reveals the significant contribution of the molecular wavefunction at short internuclear distances. Our findings highlight the potential of Feshbach resonances in providing precise information on short- and intermediate-range molecular couplings and wavefunctions. We also present measurements of spin-spin coupling in p-wave Feshbach resonances in a Li6 mixture and three-body-losses in a non-thermalizing regime. |
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F01.00118: Long-Range Behavior of 3- and 4-body Fermionic Systems near Unitarity Michael D Higgins, Chris H Greene Few interacting fermions near or at unitarity have been extensively studied in the context of atomic physics. One class of systems near unitarity is the BEC-BCS crossover problem, where the two-body singlet s-wave scattering length (a) is large compared to the range (r0) of the interaction (|a/r0|>10). This work is also relevant to the few-neutron problem in nuclear physics. These systems are studied in the adiabatic hyperspherical framework using an explicitly-correlated Gaussian basis. Through an analysis of the lowest few adiabatic potentials, the long-range behavior of the potentials exhibit universal behavior through a deviation from the repulsive ρ-2 centrifugal barrier of the form Ca/ρ3, where ρ is the hyperradius and C depends only on system size and particle statistics. This long-range coefficient is extracted for both 3-body and 4-body systems through an analysis of adiabatic hyperradial potentials, computed using a correlated Gaussian hyperspherical method. The implications of this universal long-range behavior on low-energy N-body continuum scattering phaseshifts and the Wigner-Smith time delay are also explored. |
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F01.00119: Numerical studies of thermalization in few-body Rydberg interactions Alicia Handian, Nina P Inman, Thomas Carroll, Michael W Noel Recently, Faoro et al. [Nat. Commun. 6, 8173 (2015)] and Tretyakov et al. [Phys. Rev. Lett. 119, 173402 (2017)] observed three-body resonances among ultracold Rydberg atoms and Liu et al. [Phys. Rev. Lett. 124, 133402 (2020)] studied the time-dependence of the two-, three-, and four-body cases. In this system, the two-body dipole-dipole interaction is of the form p + p → s + s'. If this is slightly detuned, additional atoms can make up for the energy gap by effectively transitioning to the nearby p' state. Since this process requires four energy levels, it is computationally expensive to simulate. We have developed a simplified three-level model to explore the dynamics of the time-evolution and thermalization of these few-body interactions. We present the results of our simulations along with comparison to experiment where possible. |
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F01.00120: High-Sensitivity Measurements of Franck-Condon Factors Enabled by Optical Cycling Benjamin Augenbraun, Zack Lasner, Nathaniel Vilas, Timothy Steimle, John M Doyle Recent experiments have successfully laser cooled a variety of molecules, including diatomic, linear triatomic, and symmetric top species. Laser cooling and trapping can require repeatedly scattering more than 10,000 photons per molecule, so all potential losses above the level of 1 part in 105 must be identified and repumped to mitigate losses. Here, we use optical cycling to measure vibrational branching ratios of polyatomic molecules, achieving relative intensity sensitivities at the 10-5 level. The apparatus described can be adapted to probe any laser coolable molecule simply by tuning two laser wavelengths. Using CaOH, YbOH, and CaOCH3 as examples, we discuss how these high-precision branching ratio measurements allow us to infer values for Renner-Teller and (pseudo)-Jahn-Teller parameters in polyatomic molecules. |
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F01.00121: GENERAL PRECISION MEASUREMENTS
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F01.00122: Ultra-Heavy Dark Matter Search with Electron Microscopy of Geological Quartz Reza Ebadi, Anubhav Mathur, Erwin Tanin, Mason C Marshall, Aakash Ravi, Raisa Trubko, Nicholas Tailby, Roger Fu, David F Phillips, Surjeet Rajendran, Ronald L Walsworth Despite ever-improving sensitivities, the simplest dark matter candidate particles have not been observed, motivating searches for a wider range of possible dark sectors. Self-interactions within the dark sector could clump dark matter into heavy composite states with low number density, leading to a highly suppressed event rate for existing direct detection experiments. The large interaction cross section of such ultra-heavy dark matter results in a distinctive and compelling signature: long, straight damage tracks as the composite dark matter passes through, and continuously scatters off, the surrounding matter. We propose using geologically old quartz samples as detectors for ultra-heavy dark matter. The advantage of this search strategy is two-fold: the age of the sample provides a large exposure time, and thus compensates for the ultra-heavy dark matter's low number density; and the unique geometry of the damage track serves as a high-fidelity background rejection tool. In our work, we describe a high-resolution robust readout method based on electron microscopy, characterize the most favorable geological samples for this approach, and study its reach in a simple model of the dark sector. |
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F01.00123: Isotope Shift Measurements in Ca$^+$ S. Charles C Doret, Paige K Robichaud, Matthew Roychowdhury We report progress towards a precise measurement of the isotope shifts in the 4$^2$S$_{1/2}\rightarrow$ 3$^2$D$_{3/2}$ 732 nm electric quadrupole transition in Ca$^+$. We co-trap two isotopes and simultaneously excite both ions using frequency sidebands on a single laser, dramatically reducing systematic uncertainties from many sources such as laser frequency drift and magnetic field instabilities. Such measurements have the potential to reach Hz-level precision or better; when combined into a King Plot, these two measurements can enable exacting tests of King's linearity, offering a path toward probing new physics beyond the Standard Model and also providing benchmarks for ever-improving theory of atomic and nuclear structure. |
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F01.00124: The HUNTER Sterile Neutrino Search Experiment: 131-Cs Magneto-Optical Trap Development Eddie Chang, C J Martoff, Eric R Hudson, Paul Hamilton, Peter Smith, Christian Schneider, Andrew L Renshaw, Peter D Meyers, Basu Lamichhane, Francesco Granato, Xunzhen Yu, Frank Malatino, Victoria M Palmaccio The HUNTER experiment (Heavy Unseen Neutrinos by Total Energy-Momentum Reconstruction) is a search for sterile neutrinos with masses in the keV range. The neutrino missing mass will be reconstructed from 131-Cs electron capture decays occurring in a magneto-optically trapped (MOT) sample. Reaction-microscope spectrometers will detect all charged decay products with high solid angle efficiency, and fast scintillators read out by silicon photomultiplier arrays will detect x-rays, each with sufficient resolution to reconstruct the neutrino missing mass. The short half-life of about 9.5 d of 131-Cs paired with the requirement to run the experiment continuously for order one year to obtain the target sensitivity present special challenges for the MOT. The 131-Cs MOT will be actively controlled to meet the runtime requirement, and an efficient orthotropic oven has been developed especially for the source material. |
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F01.00125: An accurate Rabi vector magnetometer Christopher H Kiehl, Tobias S Thiele, Daniel Wagner, Cindy A Regal, Svenja Knappe Many vector magnetometry applications, including magnetic anomaly detection, navigation, bio-imaging, and space exploration require directional accuracy. A variety of magnetometers achieve vector operation by referencing to mechanical references, where machining tolerances and drifts limit vector accuracy. Known solutions to these systematics are scalar calibrations that involve physical rotations of the magnetometer system and absolute references such as the crystal axes in NV centers. In this work, we demonstrate an approach to accurate vector magnetometry that uses a microwave polarization ellipse (MPE) as an absolute 3D reference. We exploit the hidden directional information of an unknown magnetic field contained in the Rabi frequencies of selected hyperfine transitions of Rb 87 that are driven by the MPE. These measurements take place in a heated microfabricated vapor cell embedded within a microwave cavity. By continuously sensing the Faraday rotation of a far-detuned probe beam, we record sequential Rabi frequencies every millisecond enabling vector sensitivities down to the 30 μRad/sqrt√Hz. Importantly, we extract systematics such as coil system and MPE drifts, pressure shifts, and Stark shifts from an accumulation of Rabi oscillations driven at various microwave detunings. |
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F01.00126: Pulse Schemes for Robust Atomic Fountain Interferometry Michael H Goerz, Mark Kasevich, Vladimir Malinovsky Atomic Fountain Interferometry is the state-of-the-art technology for the measurement of gravitational gradients and accelerations with unprecedented precision. It operates by launching a cloud of atoms into a free-fall-tower, using laser pulses acting as the equivalent of beamsplitters and mirrors to separate the cloud into a superposition of two momentum space pathways. However, signal contrast is limited by variations in the initial velocity of the atoms in the cloud and variations in the laser amplitude over the cross-section of the cloud. An ideal, robust pulse scheme must implement separation, mirroring, and recombination of the atoms to high precision over a realistic range of these variations. Here, we analyze the robustness of analytic pulse schemes, starting with the predominantly used sequence of Rabi pulses. We show that using rapid adiabatic passage as an alternative analytical pulse scheme leads to a significant improvement in robustness. Going beyond analytical schemes, we explore numerical optimal control theory to generate robust pulse schemes. We formulate the most general control conditions for the implementation of an interferometer. This allows us to show how phase errors induced by the variations in the Hamiltonian for different atoms in the cloud may be mitigated. We conclude by comparing the robustness of numerical control schemes with the best analytic schemes. |
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F01.00127: Study of Wavefront Aberrations for MAGIS-100 Laser Beam Delivery System Yiping Wang, Natasha Sachdeva, Jonah Glick, Tejas Deshpande, Kenneth DeRose, Tim Kovachy The MAGIS-100 experiment is a 100-m tall atom interferometer being built at Fermilab with a goal to measure gravitational waves in the mid-band frequency range of 0.3--3~Hz which is between the band for LIGO and LISA. For atom interferometry, pulses of light are used to create the atom optics equivalents of beam-splitters and mirrors. Laser wavefront aberrations cause phase distortions across the Sr atom cloud and result in loss of contrast and systematic errors in the interferometer phase. In this poster, we present simulation studies of the propagation of laser beam perturbations through the MAGIS-100 laser beam delivery system in order to determine the beam aberrations at the locations of the atoms. The effect of these aberrations are simulated by numerically evaluating the Rayleigh-Sommerfeld diffraction integral using the FFT convolution theorem. We studied spatial filtering of the beam by free-space propagation in the MAGIS-100 beam delivery system and the effects of specific aberrations such as localized defects and spherical aberrations in optical components. These simulations informed a design of the beam delivery system that minimizes the aberrations experienced by the atoms. |
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F01.00128: Multi-path interferometers with ytterbium Bose-Einstein condensates in optical lattices Anna Wirth-Singh, Tahiyat Rahman, Daniel Gochnauer, Andrew Ivanov, Subhadeep Gupta We present progress on the development of a vertical three-path contrast interferometer with ytterbium Bose-Einstein condensates for a fine structure constant measurement, building upon previous work in a horizontal geometry [1]. Vertically-oriented diffraction beams allow for larger momentum separation and longer interaction times, and thus a more sensitive interferometer. However, the use of a heavy atom creates undesirably large momentum spread in the vertical direction of the BEC source due to gravity. We discuss two techniques that we have used to solve this problem: gravity compensation via a shaped optical potential, and a pulsed optical potential to act as a matter-wave lens resulting in delta-kick cooling (DKC). The DKC technique reduced the vertical momentum spread by a factor of six, and this improvement is further supported by nearly six-fold improvement in the coherence time measurement by Ramsey interferometry [2]. We also present our observations of resonances and anti-resonances in Bloch oscillation efficiency due to multipath Landau-Zener-Stuckelberg interference, together with a theoretical modelling of the effect, for large momentum transfer for high precision interferometry. |
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F01.00129: Optical Aberration and Laser Pointing Jitter Mitigation for MAGIS-100 Jonah Glick, Tejas Deshpande, Natasha Sachdeva, Kenneth DeRose, Yiping Wang, Tim Kovachy MAGIS-100 is a 100 meter baseline atom interferometer which will search for wavelike dark matter, serve as a prototype gravitational wave detector in the 0.3-3 Hz frequency range, and realize large scale quantum superpositions. The interferometer will be assembled in the vertical MINOS access shaft at Fermilab, and will be mediated by a single-photon transition on the clock resonance of strontium. The space-time area enclosed by the interferometer arms can be increased with large momentum transfer pulse sequences, but jitter in the pointing of the interferometer beam and inhomogeneity in the laser phase and intensity profiles can limit the total number of pulses that can be performed. We present a design of the beam delivery system for MAGIS-100 which provides spatial mode cleaning by free-space in-vacuum propagation, minimizes subsequent induced aberrations with ultra-high-quality in-vacuum optics, provides Coriolis force compensation with piezo-controlled tip-tilt mirrors, and uses stable support structures to suppress the pointing jitter and frequency noise response of the interferometer beam from seismic drives. |
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F01.00130: Quantum-Enhanced Sensing with Sodium Spinor Bose-Einstein Condensates Shan Zhong, Hio Giap Ooi, Qimin Zhang, John E. Moore-Furneaux, Grant Biedermann, Arne Schwettmann We present our progress on interferometry with entangled atoms in our Na spinor Bose-Einstein condensate, useful for quantum-enhanced sensing. In our experiments, pairs of entangled atoms with magnetic quantum numbers mF =+1 and mF =-1 are generated from pairs of mF = 0 atoms via spin-exchange collisions. The collisions can be controlled via microwave dressing. We present our data on interferometry in spin space, where the spin states are overlapping in the trap, using seeded initial states. We also present our progress on implementing a light-pulse atom interferometer, where the entangled clouds will be spatially separated and recombined, useful for inertial sensing. |
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F01.00131: Precision Science with Ultracold Strontium Dimers Brandon Iritani, Kon H Leung, Emily Tiberi, Tanya Zelevinsky Molecules offer a new paradigm for precision measurements. Homonuclear alkaline-earth dimers are an attractive species owing to their amenability to ab initio quantum chemistry modeling, the natural existence of dipole-forbidden vibrational transitions, molecular subradiance, and narrow triplet electronic states. We demonstrate how light shifts induced by the optical lattice trap on a narrow vibrational Raman transition can be used to accurately determine molecular polarizability ratios and transition strengths. We have mapped out all 63 vibrational states with J=0 and J=2 belonging to the X1Σg+ ground potential in 88Sr2, and we compare the binding energies to ab initio calculations. We also report the all-optical creation of strontium dimers in the absolute rovibrational ground state via a singlet dominant channel in (1)0u+ using STIRAP and discuss prospects for optical trapping in a mid-IR magic lattice to maximize the coherence time of the molecular clock states. |
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F01.00132: Driving forbidden vibrational transitions in O2+ Annika Lunstad, Boran Kuzhan, Addison Hartman, Ethan Spingarn, David Hanneke Some vibrational transitions in molecules have the potential to serve as optical clocks or as probes for new physics.[1] The vibrational overtones in homonuclear molecules such as O2+ are electric-dipole forbidden and thus intrinsically narrow and immune from some systematic shifts.[2] Here, we present our experimental investigations of these overtones in a pulsed molecular beam. Photoionization of the beam's cold neutral molecules produces state-selected molecular ions, while dissociation and time-of-flight mass spectrometry provide detection. Our goal is to reduce the measurement uncertainty in the vibrational frequency with the beam apparatus before moving to high-precision spectroscopy in an ion trap. |
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F01.00133: Observation and laser spectroscopy of ytterbium monomethoxde, YbOCH3 Benjamin Augenbraun, Zack Lasner, Alexander J Frenett, Hiromitsu Sawaoka, Anh Le, Timothy Steimle, John M Doyle We describe a laser spectroscopic study of ytterbium monomethoxide, a species of interest to search for time-reversal symmetry violation using laser-cooled molecules. We have performed measurements of vibrational structure in the low-lying electronic states, vibrational branching ratios for several electronically excited vibronic states, and radiative lifetimes of low-lying electronic states. In addition, we have recorded the rotationally-resolved high-resolution excitation spectrum of the A 2E1/2 - X 2A1 band. Ab initio calculations are used to aid the assignment of vibronic emission bands and provide insight into the electronic and vibrational structure. We compare the structure of YbOCH3 to the isoelectronic species YbF and YbOH, as well as to the previously studied alkaline-earth monomethoxides. Finally, we discuss how our results open a path to increased sensitivity to P- and/or T-violating physics in future measurements. |
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F01.00134: PbF electric field dependent g-factor & Zeeman shifts Richard J Mawhorter, Vera Baturo, Alexander Petrov, Priyanka M Rupasinghe, Sean T Jackson, Trevor J Sears, Jens-Uwe Grabow The electric field dependent g-factor and the electron electric dipole moment (eEDM)-induced Stark splittings for the lowest rotational levels of 207PbF and 208PbF are calculated. Observed and calculated Zeeman shifts for 207PbF are found to be in very good agreement [1], as has earlier been shown for 208PbF [2]. These findings further substantiate previous proposals that the 207PbF hyperfine sublevels provide a promising system for the eEDM search and related experiments [3,4]. Progress on a global fit for the 4 stable PbF isotopologues including high vibrational state data will also be presented. |
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