Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session N65: Bose-Einstein Condensates I: Interferometry, and Nonlinear Waves |
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Sponsoring Units: DAMOP Chair: Yiqi Wang, Yale University Room: Room 414 |
Wednesday, March 8, 2023 11:30AM - 11:42AM |
N65.00001: Improving the performance of cold-atom inertial sensors and gravimeters using robust control Russell P Anderson, Stuart S Szigeti, Philip Light, Nicholas P Robins, Jack Saywell, Max S Carey, Karandeep Gill, Patrick Everitt, Calum D Macrae, Richard W Rademacher, Alexander Rischka, Michael Hush, Michael Biercuk Large momentum transfer (LMT) atom-optical beamsplitters and mirrors—implemented via Bragg diffraction—increase the space-time area enclosed by atom interferometers, offering a promising means of improving the precision of cold-atom inertial sensors. However, to date LMT has not improved absolute cold-atom inertial sensitivity, due to the stringent velocity-selectivity of LMT Bragg pulses making high contrast atom interferometry with appreciable atomic flux extremely challenging. In this work, I will present theoretical and experimental results showing how error-robust quantum control can be used to overcome these traditional limitations on LMT Bragg atom interferometry. Our unique approach to quantum hardware optimisation and operation allows us to design LMT pulses with increased velocity acceptance and improved robustness to laser intensity inhomogeneity. We demonstrate that our control solutions provide > 10X improvement in measurement sensitivity over Gaussian Bragg pulses at 102 ?k momentum separations, and further enable operation at longer interrogation times and without velocity selection of the initial cold thermal atomic source. Our results show how quantum control at the software level can improve future cold-atom inertial sensors, enabling new capabilities in navigation, hydrology, and space-based gravimetry. |
Wednesday, March 8, 2023 11:42AM - 11:54AM |
N65.00002: High Power, Phase Stabilized, Frequency Agile Laser System for Gravitational Wave and Dark Matter Detection Using Atom Interferometry (MAGIS-100) Kenneth DeRose MAGIS-100 is 100-meter atom interferometer currently being built at Fermilab which will leverage modern atom optics techniques to search for oscillations in fundamental constants and time-dependent, equivalence-principle-violating forces which are key signatures of several ultra-light dark matter candidates. In addition, the interferometer can test the coherence limits of spatially separated wave packets and will also serve as a prototype gravitational wave detector in the frequency band between the peak sensitivities of LIGO and LISA. Generation and precise control of meter-separated quantum atomic superpositions within the interferometer requires an agile laser system able to rapidly shift the optical frequency up to a rate of 100 GHz/s while maintaining a phase lock to our static frequency comb. To meet the power requirement of the experiment, two lasers coherently locked must be robust to these rapid frequency shifts. Furthermore, the laser spatial mode is cleaned through fiber coupling and long free space propagation in vacuum. Frequency noise introduced by the fiber is suppressed with a PID lock. |
Wednesday, March 8, 2023 11:54AM - 12:06PM |
N65.00003: Sensitivity of a Double-Target BEC Rotation Sensor Mark A Edwards
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Wednesday, March 8, 2023 12:06PM - 12:18PM |
N65.00004: Condensate and Soliton stability in a 1D lattice with density-dependent hopping William N Faugno, Tomoki Ozawa The nonlinear Schrodinger equation is a ubiquitous model, providing insight into a variety of systems, ranging from nonlinear optics to Bose-Einstein condensates. Motivated by a previously proposed Floquet protocol, we have investigated a discrete nonlinear Schrodinger equation where the role of the interaction is played by a density-dependent hopping, equivalent to a dynamical gauge field. The few particle physics of this system have been previously studied and found to exhibit topology induced by the interaction. Here we explore the many-body physics. We find that in the limit of the low gauge coupling, the ground state is described by a plane wave while for large gauge couplings, the ground state corresponds to a soliton. Uniquely this system has soliton solutions while the plane wave spectrum is completely non-interacting. We explore the stability of the condensate plane waves to linear perturbations from both the classical linearization and the quantum Bogoliubov transformation. Finally, we elucidate unique nonreciprocal physics brought by non-Hermiticity in the gauge coupling. |
Wednesday, March 8, 2023 12:18PM - 12:30PM |
N65.00005: Artificial Intelligence for Atom Interferometry (AI^2) Sanha Cheong, Sean Gasiorowski, Michael Kagan, Murtaza Safdari, Ariel Schwartzman, Maxime Vandegar, Natasha Sachdeva, Yiping Wang, Timothy Kovachy, Jonah Glick, Arthur Perce MAGIS-100 is a proposed experiment under construction at Fermilab which will use interference fringes imprinted on cold atom clouds to sense physics signals, such as mid-frequency band gravitational waves and ultralight dark matter. To maximize the reach of this new experiment, a sophisticated set of tools must be developed for imaging, data reconstruction, and simulation. Modern machine learning/AI techniques offer innovative and powerful solutions to this diverse set of problems. In this talk, we present 3D reconstruction techniques for atom clouds using a differentiable ray-tracing simulator in conjunction with methods from modern neural rendering. Such techniques, used along with a recently developed light-field imaging device [arXiv:2205.11480], enable 3D reconstruction of cold atom clouds in a single camera shot. We further present a differentiable atomic simulator, which characterizes a dominant experimental systematic via a gradient-based fitting of wavefront aberrations in the lasers used for the interferometry. Several extensions to the above work are also discussed. |
Wednesday, March 8, 2023 12:30PM - 12:42PM |
N65.00006: Laser Beam Delivery for 100-Meter Baseline Clock Atom Interferometry (MAGIS-100) Jonah Glick, Zilin Chen, Timothy Kovachy, Natasha Sachdeva, Tejas Deshpande, Yiping Wang, Kenneth DeRose 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, where an 8 W laser will split the wave function of strontium atom clouds via the 698nm clock resonance. The ultimate sensitivity of the apparatus is limited in part by jitter in the pointing of this interferometer laser, aberrations in its wavefront, and Coriolis forces emerging from the rotation of the earth. We present the design and a prototype test of the beam delivery system for MAGIS-100, which provides spatial mode cleaning by free-space in-vacuum propagation, minimizes subsequently 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 and frequency jitter of the interferometer laser caused by seismic drives. |
Wednesday, March 8, 2023 12:42PM - 12:54PM |
N65.00007: Robust Atom Optics for Strontium-88 Atom Interferometers Garrett Louie, Zilin Chen, Timothy Kovachy Light pulse atom interferometers using alkaline earth atoms have numerous applications, ranging from tests of fundamental physics to mobile surveying. In practice, their performance is limited by laser noise and inhomogeneities across the atom cloud, causing atom loss and phase errors which accumulate with repeated pulses. In this talk, we report design and simulation studies of numerical quantum optimal control (QOC) mirrors and beamsplitters for use with large momentum transfer (LMT) atom interferometers based on multi-photon Bragg (461 nm) and single-photon (689 nm) transitions in Sr-88. These pulses are simultaneously robust to multiple sources of noise including laser amplitude fluctuations, momentum variation, and magnetic field or polarization errors, allowing longer pulse sequences and operation in noisy environments. We compare loss of simulated fringe contrast in LMT sequences to demonstrate the advantage of optimized pulses over square, Gaussian, and composite pulses. Once implemented, such QOC atom optics may allow the next generation of atom interferometers to overcome previously unavoidable limitations. |
Wednesday, March 8, 2023 12:54PM - 1:06PM |
N65.00008: Autonomous analysis of excitations in Bose-Einstein Condensates Lisa Ritter, Amilson Fritsch, Ian B Spielman, Justyna P Zwolak Solitons are non-dispersive waves that can occur in many systems, at scales ranging from microscopic, to terrestrial and even astronomical. In Bose-Einstein condensates (BECs), the parameters governing the atomic cloud are under strict experimental control and can be manipulated to contain solitonic excitations including conventional solitons, vortices, and many more. Current research looks to understand the dynamics of solitonic excitations by producing images of atomic clouds that need to be analyzed. Recent work [1] has developed machine learning algorithms to determine if solitonic excitations were created in a BEC, and to classify them into physically-motivated subclasses, such as a well defined single soliton, a partial soliton, or solitonic vortex. This presentation will discuss our current work across two fronts. First, improvements have been made in estimating the quality of multiple solitons appearing close together and thus interfering with each other. For such cases the standard quality metric introduced in Ref. [1] tends to rate both solitons as "bad" quality which is often incorrect. Next, we are testing clustering methods to better assess the expected number of physically-motivated subclasses and random decision forests to aid with proper parameter thresholds for each subclass. Our goal is to make the soliton detection software package [2] more adaptable to a wider array of BEC experiments. |
Wednesday, March 8, 2023 1:06PM - 1:18PM |
N65.00009: Multi-state interferometric measurement of nonlinear AC Stark shift Junnosuke Takai, Kosuke Shibata, Naota Sekiguchi, Takuya Hirano In spin measurement using Faraday rotation of near-resonant probe light, the probe can change the atomic spin state. Nonlinear spin evolution due to quadratic AC Stark shift causes spin change harmful in precise measurements and quantitative evaluation of this change is important. |
Wednesday, March 8, 2023 1:18PM - 1:30PM |
N65.00010: Laser Wavefront Metrology with Point-source Atom Interferometry Yiping Wang Wavefront aberration is one of the major systematic errors in atom interferometry for precision measurements. Aberrations in the atom optics laser beam result in laser phase shifts that depend on the position of the atom cloud with respect to the aberrations, leading to systematic phase shift errors and to dephasing. |
Wednesday, March 8, 2023 1:30PM - 1:42PM |
N65.00011: Quantum hydrodynamics of spin-current squeezing in spinor Bose-Einstein condensates Emi Yukawa Hydrodynamic description of spinor Bose-Einstein condensates provides a mean-field description equivalent to the multi-component Gross-Pitaevskii equation. We generalize it in the second quantized formalism so that it can treat highly nonclassical systems that cannot be analyzed by the perturbation theory. This formalism can be used to explore strongly quantum-mechanically correlated systems such as spin squeezed states and entangled spin currents propagating to the different directions. We numerically solve the second quantized hydrodynamic equations under the single-mode approximation and show that the spin-current squeezing can be realized in spin-squeezed systems. |
Wednesday, March 8, 2023 1:42PM - 1:54PM |
N65.00012: Self-Bound Cold Atom Films, Bubbles, Tori, and Meta-Materials Saad Khalid Quantum droplets are Bose-Einstein condensates which are stabilized due to the effects of quantum fluctuations. We show that a variety of stable structures can be constructed from quantum droplets. The droplet can be stretched into a curved film using a quadrupolar field and can form spherical and toroidal bubbles when filled with another immiscible BEC. We also study arrays of BEC clusters stabilized inside a quantum droplet medium and show that it can form an interlocking supersolid of the droplet and the BEC. We discuss experimental procedures to create these structures. Our work serves as a blueprint for the creation of Quantum Gas Meta-Materials. |
Wednesday, March 8, 2023 1:54PM - 2:06PM |
N65.00013: Scaling in reactions involving unitarity bosons Ruchira Mishra, Dam T Son We discuss the behaviour of the rates of scattering processes where three identical bosons at unitarity are emitted in the final state, extending the recent work on ``unnuclear physics'' [1] to chemical reactions involving helium atoms. Despite the presence of the Efimov effect, which breaks scale invariance down to a discrete scale invariance in the bound state spectrum, we still find a scaling regime in the behaviour of the rates of these processes. |
Wednesday, March 8, 2023 2:06PM - 2:18PM |
N65.00014: Quantum XY Magnetism in a Two-dimensional Rydberg Atom Array Marcus Bintz, Cheng Chen, Guillaume Bornet, Gabriel Emperauger, Lucas Leclerc, Vincent S Liu, Pascal Scholl, Daniel Barredo, Johannes Hauschild, Shubhayu Chatterjee, Michael Schuler, Andreas M Läuchli, Michael P Zaletel, Thierry Lahaye, Norman Y Yao, Antoine Browaeys Optical tweezer arrays of strongly-interacting Rydberg atoms are an emerging platform for studying quantum magnetism. In this talk, we present an experimental and theoretical investigation of a new two-dimensional, square lattice system of up to 100 atoms, where each effective spin-1/2 is encoded in a pair of Rydberg states. The ordinary dipole-dipole interaction between two such Rydberg atoms then manifests as a long-range XY Hamiltonian, featuring a continuous U(1) spin-rotation symmetry. We design and use an adiabatic preparation scheme to realize low-temperature states of this XY model - for both ferromagnetic and antiferromagnetic XY couplings - and validate the efficacy of our protocol with extensive numerical simulations. We also demonstrate how to inject additional energy into the isolated system via a controlled quantum quench. Remarkably, with ferromagnetic XY coupling we observe off-diagonal long-range order in the spin correlation functions, even at finite effective temperature. Spontaneously breaking a continuous symmetry in this way is ordinarily forbidden by the Hohenberg-Mermin-Wagner theorem; here, the underlying long-range interactions are key. |
Wednesday, March 8, 2023 2:18PM - 2:30PM |
N65.00015: A Universal Theory of Spin Squeezing Maxwell Block, Bingtian Ye, Brenden Roberts, Sabrina Chern, Lode C Pollet, Emily Davis, Bertrand I Halperin, Norman Y Yao Quantum metrology makes use of many-body entangled states to perform measurements with greater precision than would be possible using only classically correlated particles. Discerning states suitable for quantum metrology is a delicate challenge: nearly all states in Hilbert space are highly entangled, but nearly none of them exhibit the structured entanglement required for enhanced sensing. Identifying universal principles for finding metrologically-useful states remains an important challenge, especially in the context of efficiently preparing such states from unentangled product states. One such principle stems from the observation that the metrological gain from a pure state is fundamentally connected to spontaneous symmetry breaking. In this work, we apply this principle to the case of U(1) symmetry breaking and provide extensive numerical and analytic evidence for the following conjecture: Finite temperature easy-plane ferromagnetism (i.e. XY magnets) enables scalable spin squeezing. In particular, we consider the quench dynamics of a low-energy initial state and show it undergoes squeezing as a precursor to the equilibration of long-range order. Our main results are threefold. First, we establish a phase diagram for spin-squeezing, with a sharp transition distinguishing scalable squeezing from non-squeezing. Second, we demonstrate that this transition precisely coincides with the phase boundary for finite temperature XY order. Finally, we show that the squeezing manifests a novel scaling with system size that leads to a sensitivity ~ N-7/10, in between the standard quantum limit ~ N-1/2 and the Heisenberg limit ~ N-1. |
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