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 S07: Quantum SimulationLive
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Chair: Sona Najafi, IBM |
Thursday, June 3, 2021 10:30AM - 10:42AM Live |
S07.00001: Realizing Su-Schrieffer-Heeger topological edge states in Rydberg-atom synthetic dimensions Soumya K Kanungo, J D Whalen, Y Lu, M Yuan, S Dasgupta, F B Dunning, K R A Hazzard, T C Killian Synthetic dimensions based on coupled Rydberg levels in ultracold atoms can be a powerful tool for quantum simulation. We demonstrate this platform by implementing the Su-Schrieffer-Heeger (SSH) Hamiltonian on a Rydberg strontium atom. The Rydberg levels are interpreted as synthetic lattice sites and the tunneling is introduced through resonant millimeter-wave couplings. The millimeter-wave amplitudes control the tunneling amplitudes whereas frequency detunings of the millimeter waves from resonance control the on-site potential. We attain a configuration with symmetry-protected topological edge states by using an alternating weak and strong tunneling pattern, with weak tunneling to edge lattice sites. The band structure is probed through optical excitation to the Rydberg levels from the ground state, which reveals topological edge states at zero energy. We verify that edge-state energies are robust to perturbation of tunneling-rates, which preserves chiral symmetry, but can be shifted by the introduction of on-site potentials. The scope of Rydberg-atom synthetic dimensions in realizing higher dimensional systems, non-trivial spatial and band structure topologies, artificial gauge fields and many-body physics with long-range interactions in optical tweezers will also be discussed. |
Thursday, June 3, 2021 10:42AM - 10:54AM Live |
S07.00002: Topology with Synthetic dimensions in Rydberg Atoms Soumya K Kanungo, Joseph D Whalen, Yi Lu, Ming Yuan, Sohail Dasgupta, F B Dunning, Tom C Killian, Kaden R Hazzard The recent realization of a 6-site synthetic dimension with Rydberg states of ultracold 84Sr atoms, using microwaves as synthetic tunnelings between synthetic lattice sites demonstrates a new platform to study topological quantum matter. The ability to adjust each tunneling rate and on-site potential offers capabilities to create not only conventional topological band structures, but also Floquet bands, disorder, and interacting topological systems. To harness this potential, we must understand to what extent the experimental platform matches its idealized model of a synthetic dimension. We do this by calculating the effects of going beyond the rotating-wave-approximation, unwanted nearby magnetic levels, and possible decoherence mechanisms, and we compare with experimental measurements. We conclude that these pose no significant obstacles to scaling to more levels and atoms, making the platform promising to study synthetic quantum matter. Looking forward, we describe how interacting topological matter can be studied by loading these atoms in microtraps and exploiting the strong dipole-dipole interaction of Rydberg atoms. |
Thursday, June 3, 2021 10:54AM - 11:06AM Live |
S07.00003: Quantum phases of a kagome-lattice Rydberg atom array Rhine Samajdar, Wen Wei Ho, Hannes Pichler, Mikhail Lukin, Subir Sachdev We analyze the zero-temperature phases of an array of neutral atoms on the kagome lattice, interacting via laser excitation to atomic Rydberg states. Density-matrix renormalization group calculations reveal the presence of a wide variety of complex solid phases with broken lattice symmetries. In addition, we identify a regime with dense Rydberg excitations that has a large entanglement entropy and no local order parameter associated with lattice symmetries. From a mapping to the triangular lattice quantum dimer model, and theories of quantum phase transitions out of the proximate solid phases, we argue that this regime could contain one or more phases with topological order. Our results provide the foundation for theoretical and experimental explorations of crystalline and liquid states using programmable quantum simulators based on Rydberg atom arrays. |
Thursday, June 3, 2021 11:06AM - 11:18AM Live |
S07.00004: Effect of atom motion in Rydberg-atom arrays Zewen Zhang, Ming Yuan, Bhuvanesh Sundar, Kaden R Hazzard Ultracold Rydberg atoms in optical lattices and tweezer arrays are a promising platform to study quantum spin models. Ref. [1] suggests that a two-particle “interaction noise” is required to reproduce their experimentally observed Rydberg-atom dynamics, but it provided only a phenomenological description of the effect. To understand these effects without any fitting or phenomenological assumptions, we calculate dynamics of Rydberg atom spin models including atom motion, using a discrete truncated Wigner approximation. Our calculations reveal that motional effects cause deviations from the nominal quantum Ising model describing the systems. The results semi-quantitatively agree, without fitting, with Ref. [1]’s experiments and noise model. We calculate how motional effects depend on time scale, atomic mass, lattice or microtrap depth, Rydberg interactions, and other important experimental variables, which will allow this theory to guide future experimental design. We show that although trap depth mitigates these decoherence sources, the motional effects are nevertheless relevant for ongoing experiments in microtrap arrays. |
Thursday, June 3, 2021 11:18AM - 11:30AM Live |
S07.00005: Emerging Gauge Fields caused by Density-Dependent Peierls Phases in Rydberg Arrays Simon Ohler, Maximilian Kiefer-Emmanouilidis, Michael Fleischhauer It has been shown experimentally that spin-orbit coupling in systems of Rydberg atoms gives rise to density-dependent Peierls Phases [Lienhard et al., PRX 10, 021031 (2020)] in the hopping process of Rydberg spin excitations. In this work we expand on this and study a one-dimensional zig-zag ladder system of identical spin-orbit coupled Rydberg atoms exhibiting such a density-dependent hopping in addition to a van-der-Waals like repulsion. We show that beyond the mean-field level, the density-dependent hopping generates a dynamical gauge field. In the liquid state, where hopping processes dominate, the emerging gauge field displays liquid-like flux correlations. In the ordered phase, where repulsion dominates, a flux lattice with long-range correlations is formed. |
Thursday, June 3, 2021 11:30AM - 11:42AM Live |
S07.00006: Programmable quantum control with tweezers in a Hubbard-regime optical lattice Aaron W Young, William J Eckner, Nathan A Schine, Adam Kaufman We present a new platform that combines the tools of quantum gas microscopy with optical tweezers and alkaline-earth atoms, where tweezer-implanted atoms in a Hubbard-regime optical lattice are free to tunnel in 2D, and explore a region that spans many hundreds of lattice sites. The tweezers allow for programmable modification of the lattice with single-site resolution, which we leverage in studies of search via 2D quantum random walk. Beyond enabling the study of Hubbard physics in 2D, the lattice further complements the tweezers in terms of providing power-efficient generation of many (>2000) traps that are compatible with robust 3D ground-state cooling, low loss imaging, and high-fidelity manipulation of the optical clock qubit. This enables parallel work conducted in our group that engineers interactions and entanglement between optical clock qubits via Rydberg excitations. When combined with the half-minute scale optical clock coherence recently demonstrated with this apparatus [1], these tools provide the unique capability to engineer entanglement on an internal degree of freedom that persists on timescales that are long compared to the tunneling time. This opens the door to a variety of exciting avenues, including engineering many-body oracles for search, exploring extended Hubbard models, and studies of the tunneling statistics of entangled particles, including simulations of anyonic statistics. |
Thursday, June 3, 2021 11:42AM - 11:54AM Live |
S07.00007: Entanglement generation on the strontium optical clock transition in tweezer-defined 2d arrays Nathan A Schine, Aaron W Young, William J Eckner, William R Milner, Dhruv Kedar, Matthew A Norcia, Eric Oelker, Jun Ye, Adam Kaufman Entanglement generation in large arrays of neutral atoms, combined with high fidelity single particle control and detection, is a critical resource for exploration of quantum many body physics, quantum metrology, and quantum information processing. We trap bosonic strontium in a hybrid apparatus which combines the high imaging resolution, scalability, and tunneling dynamics of quantum gas microscopes with the rapid and programmable low-entropy state preparation afforded by optical tweezers. Recently, we have added the ability to drive directly from the clock state (5s5p3P0) to a Rydberg state (5sns3S1) at high Rabi frequency. We report on the resulting generation of entanglement on the optical clock transition using both detuned and adiabatically resonant Rydberg pulses, and we discuss the implications for a resulting quantum speed up in optical frequency metrology. From a many body physics perspective, this directly implements a transverse field Ising model, and we draw connections between the continuous nonlinear evolution under this model with the generation of spin squeezed and GHZ states relevant to quantum metrology and quantum information processing. |
Thursday, June 3, 2021 11:54AM - 12:06PM Live |
S07.00008: Ultrastrong light-matter interaction in a photonic crystal waveguide Andrei Vrajitoarea, Ron Belyansky, Rex O Lundgren, Seth P Whitsitt, Alexey V Gorshkov, Andrew Houck The superconducting quantum circuits platform has developed into a rich playground for building synthetic quantum materials composed of interacting microwave excitations. In this work, we apply this toolbox for exploring the physics of an artificial atom coupled to the many modes of a photonic crystal. Recently, 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, we use an emitter with a higher nonlinearity and push the coupling strength beyond the single-photon regime. Our platform consists of a fluxonium qubit galvanically coupled to a linear chain of microwave resonators. Transport measurements reveal how the propagation of a single photon becomes a many-body problem as multi-photon bound states participate in the scattering dynamics. The effective photon-photon interactions induced by the impurity emerge as we measure the inelastic scattering spectrum. Furthermore, we probe signatures of multi-mode entanglement from measured correlations in the emitted quadrature fields. This work opens a new avenue for future explorations in many-body quantum optics. |
Thursday, June 3, 2021 12:06PM - 12:18PM Live |
S07.00009: New spectroscopic probes in the Fermi-Hubbard model Fabian Grusdt, Annabelle Bohrdt, Michael Knap, Eugene Demler Spectroscopy allows direct insights into the nature of collective excitations of strongly correlated quantum systems. In this talk, I present recent developments that will allow spectroscopic probes of the 1D and 2D Fermi-Hubbard models using ultracold atoms. Specifically, angle-resolved photo-emission spectroscopy (APRES) is discussed. A new extension of ARPES is introduced which relies on a combination of different lattice modulations and allows to impart angular momentum into the system. This, in turn, is shown to reveal qualitatively new types of rotational excitation of mobile dopants in the 2D Hubbard model, which can be explained by an emergent parton structure. The talk closes by a discussion of the required temperatures to observe the newly predicted rotational resonances -- which are within reach of current experimental platforms. |
Thursday, June 3, 2021 12:18PM - 12:30PM Live |
S07.00010: The fate of the false vacuum: Finite temperature, entropy and topological phase in quantum simulations of the early universe Peter D Drummond, Bogdan Opanchuk, King Ng, Manushan Thenabadu, Margaret D Reid Despite being at the heart of the theory of the "Big Bang", the quantum field theory prediction of false vacuum tunneling has not been tested. We give a numerical feasibility study of a table-top BEC quantum simulator proposal for this effect under realistic conditions. We report the observation of false vacuum tunneling in computer simulations, and the formation of multiple bubble 'universes' with distinct topological properties. The tunneling gives a transition of the relative phase of coupled Bose fields from a metastable to a stable 'vacuum'. We include the finite temperature effects of a laboratory experiment and also analyze modulational instabilities in Floquet space. Our numerical model uses an approximate truncated Wigner (tW) method. We analyze a nonlocal observable called the topological phase entropy (TPE). A cooperative effect occurs, in which the true vacua bubbles representing distinct universes each have one or the other of two distinct topologies. The TPE initially increases with time, reaching a peak as multiple universes are formed, and then decreases with time to the phase-ordered vacuum state. This models formation of universes with one of two distinct phases, which is a possible solution to the problem of particle-antiparticle asymmetry. |
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