Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session J08: Cold Atoms in Optical LatticesLive
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Chair: Paul Hamilton, UCLA Room: Portland 255 |
Wednesday, June 3, 2020 2:00PM - 2:12PM Live |
J08.00001: Negative refraction and photonic-crystal optics in cold atomic gases Marina Litinskaya, Evgeny Shapiro Negative refraction of light is a fascinating phenomenon, since recently available in artificial solids, but not yet achieved in gases. We have shown that negative refraction can be realized in a periodically modulated cold atomic gas, in the setup similar to the scheme developed for photonic crystals. However, the intuition coming from photonic crystal optics encounters three challenges: poorly defined gas boundary and weak gas-light coupling combined with strong resonant absorption. To account for the indistinct boundary, we derive an analog of the quantum adiabatic theorem for coupled propagation of normally and negatively refracting modes and study the dynamics of energy transfer between them. We demonstrate that, by adjusting the parameters of the zones where light enters and exits the gas cloud, one can realize almost loss-less propagation of negatively refracted light in strongly absorbing gas at experimental parameters currently existing in many labs. [Preview Abstract] |
Wednesday, June 3, 2020 2:12PM - 2:24PM Live |
J08.00002: Cavity probe for single-shot detection of atom dynamics in an optical lattice Robert Niederriter, Chandler Schlupf, Paul Hamilton We propose and demonstrate a technique for real-time sub-wavelength cavity QED measurements of atom spatial distributions within the lattice sites of an optical cavity. Atoms are trapped in a red-detuned standing wave formed within an optical cavity and probed with an adjacent longitudinal cavity mode near atomic resonance. The atoms in $\sim\!10^4$ lattice sites are uniformly coupled to the probe wave, enabling global measurements to provide single-site spatial information about the atom distribution. As a demonstration of the proposed technique, we perform single-shot axial and radial temperature measurements of 20-70 $\mu$K ensembles. Axial temperature measurements are based on detecting 100-nm-scale expansion of the atom cloud from each lattice site simultaneously on a time scale of $<$10 $\mu$s after extinguishing the trapping lattice. As the cloud expands, the atom-cavity coupling changes, shifting the cavity resonance frequency. The atom dynamics are therefore imprinted on the probe beam transmission through the cavity. The continuous observation of single-site spatial dynamics enables a range of applications in optomechanics and quantum sensing. [Preview Abstract] |
Wednesday, June 3, 2020 2:24PM - 2:36PM Live |
J08.00003: Novel structures and phase transitions in a superradiant crystal Alexander Baumgartner, Davide Dreon, Xiangliang Li, Philip Zupancic, Tilman Esslinger, Tobias Donner We report on the experimental realization of a superradiant phase transition of a Bose-Einstein Condensate in a high finesse cavity with a repulsive pump-lattice, in which the destructive interference between pump and cavity fields lowers the total energy of the system. Due to lattice symmetries, the band structure plays a key role in this process, and we show that the atoms self-organize in the second band with observable consequences for the phase diagram and the atomic momentum distributions. Furthermore, in this repulsive pump regime, the addition of a running wave transverse pump gives rise to a second type of self-organization phase. We map out the rich phase diagram of the system and identify the phase transition between the two phases as a first-order transition. The dissipated photons out of the cavity lead to real-time access of the dynamics during the phase transition. In our latest experiments we utilize this dissipation channel to couple the two phases and create a dynamic instability as an additional phase. [Preview Abstract] |
Wednesday, June 3, 2020 2:36PM - 2:48PM Live |
J08.00004: State-dependent Optical Lattices for the Strontium Optical Qubit Neven Santic, André Heinz, Annie Jihyun Park, Jan Trautmann, Sergey G. Porsev, Marianna S. Safronova, Immanuel Bloch, Sebastian Blatt We demonstrate state-dependent optical lattices for the clock states in strontium at the tune-out wavelength for the $^1$S$_0$ ground state, where its dipole polarizability vanishes. Using a novel spectroscopic method, we measure an absolute frequency of 434,972,130(10) MHz for this tune-out wavelength in Sr-88, one of the most precise and accurate measurements of a tune-out wavelength to date. Our method can be applied to thermal gases of atoms, molecules, or to trapped ions. Furthermore, in a proof-of-principle experiment, we trap 3P0 atoms in a one-dimensional optical lattice at the tune-out wavelength, suppressing the effect of the lattice on ground state atoms by more than four orders of magnitude. This highly independent control over the qubit states removes inelastic excited state collisions as the main obstacle for quantum simulation and computation schemes based on the Sr optical qubit. Our results also reveal large discrepancies in the atomic data used to calibrate the largest systematic effect of Sr optical lattice clocks. [Preview Abstract] |
Wednesday, June 3, 2020 2:48PM - 3:00PM Live |
J08.00005: Defect-Free 2D Arrays of Several Hundred $^{87}$Rb Atoms in Optical Tweezers Tout Wang, Harry Levine, Alexander Keesling, Giulia Semeghini, Ahmed Omran, Sepehr Ebadi, Dolev Bluvstein, Markus Greiner, Vladan Vuletic, Mikhail Lukin Neutral atoms trapped in optical tweezer arrays have become a compelling platform for quantum simulation and quantum information processing. Recent experiments from our group have demonstrated the entanglement of up to 20 atoms and the implementation of high-fidelity multi-qubit gates via Rydberg excitations in defect-free 1D arrays of $^{87}$Rb. Recently, we have expanded our experimental capabilities to be able to produce large, defect-free arrays of several hundred atoms in programmable 2D geometries. I will describe our latest experiments with these 2D arrays of atoms, and discuss the possibilities for quantum simulation and quantum computation with this platform. [Preview Abstract] |
Wednesday, June 3, 2020 3:00PM - 3:12PM Live |
J08.00006: Anomalous Diffusion in the Integrable Fermi-Hubbard Chain Brayden Ware, Romain Vasseur, Sarang Gopalakrishnan Recent theoretical developments derived from the generalized hydrodynamics framework have predicted anomalous transport in integrable spin chains with non-Abelian rotation symmetry, such as the Heisenberg chain and the Fermi-Hubbard chain. For the Fermi-Hubbard chain, spin and charge transport is predicted to show superdiffusion with dynamical exponent $z=3/2$ at finite temperatures. Using matrix product operator-based simulations of time evolution, we verify these predictions numerically and investigate whether the anomalous transport is robust enough to be seen in cold atom experiments, considering the effects of finite size and integrability breaking perturbations. We show that signatures of the anomalous diffusion are robust and accessible at time scales, system sizes, and temperatures reachable by current experiments. [Preview Abstract] |
Wednesday, June 3, 2020 3:12PM - 3:24PM Live |
J08.00007: Calculated band structure of a bichromatic optical lattice with tunable depths and phases John Huckans We have calculated the band structure of an optical lattice composed of two commensurate overlapping lattices with tunable depth and phase differences. It is found that for certain lattice depth ratios, bandgaps are highly dependent on phase tuning between the lattices. The results of our calculations relate importantly to issues of fidelity and adiabaticity during low-level vibration excitations of ultracold atoms in optical lattices. [Preview Abstract] |
Wednesday, June 3, 2020 3:24PM - 3:36PM Live |
J08.00008: Probing non-exponential decay in a Floquet-engineered optical lattice Ethan Simmons, Alec Cao, Roshan Sajjad, David Weld Given the ubiquity of exponential decay as a description of a wide variety of physical processes, it is a surprising fact that purely exponential decay is forbidden by quantum mechanics: population dynamics must deviate from exponential time dependence at both very short and very long times. Long-time quantum corrections to exponential decay in individual metastable systems may be observable in processes ranging from negative-ion photodetachment to synthetic spontaneous emission of matter waves to emission near photonic crystal bandgaps, but a direct theory-experiment comparison for this fundamental phenomenon remains a challenge. We describe a new experimental probe of non-exponential decay dynamics, in which a non-interacting quantum gas is driven through a tunably avoided crossing between two Floquet-engineered quasienergy bands. We discuss the potential of this new tool as a means of directly measuring fundamental quantum corrections to exponential decay. [Preview Abstract] |
Wednesday, June 3, 2020 3:36PM - 3:48PM Not Participating |
J08.00009: Finite-size Scaling at First-order Superfluid to Mott-insulator Phase Transitions in Spinor Condensates Zihe Chen, Jared Austin, Zachary Shaw, Lichao Zhao, Perry Hurd, Yingmei Liu We present an experimental study on finite-size scaling effects at superfluid (SF) to Mott-insulator (MI) quantum phase transitions in antiferromagnetic spinor condensates confined by cubic optical lattices. Possessing a spin degree of freedom, atoms in antiferromagnetic spinor condensates can cross first-order (second-order) SF-MI transitions when the quadratic Zeeman energy is set at a value smaller (larger) than the spin-dependent interaction. We start every experimental cycle with an antiferromagnetic spinor condensate at its SF ground state, and monitor evolutions of spin populations as the lattice potential is quenched to a sufficiently large value where atoms enter into the MI phase. The observed quench dynamics, especially the “freeze-out” time near the phase boundary, show a power-law scaling dependence on the quench speed. We compare our observations with the quantum Kibble-Zurek model, and also study the relationship between the scaling exponents and the nature of the SF-MI phase transitions. [Preview Abstract] |
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