Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session P6: Driven Cold Gases |
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Chair: Norman Yao, University of California, Berkeley Room: 311-312 |
Thursday, June 8, 2017 2:00PM - 2:12PM |
P6.00001: A driven dissipative phase transition in an ultracold lattice gas Yogesh S Patil, Hil F H Cheung, Mukund Vengalattore Optical lattice gasses have emerged as a powerful platform for the study of correlated quantum behavior both in equilibrium and in non-equilibrium settings. Most studies to date have benefited from the isolation of these gasses from environmental sources of dissipation to realize long-lived coherent quantum dynamics. However, a growing body of theoretical work [1,2] has focused on novel forms of many-body phases arising from the interplay between coherent quantum dynamics and dissipation. Such driven, dissipative systems are predicted to exhibit quantum critical behavior, dynamical phase transitions and quantum many-body effects that lie beyond the conventional description and classification of equilibrium phase transitions. Here, we describe the realization of a metal-to-insulator transition (MIT) in an ultracold lattice gas arising from the competition between quantum coherence and dissipation in the form of tunable photon scattering. We discuss key aspects of the phase diagram of this system, novel features arising from its non-equilibrium nature and correspondences between our system and quantum percolation models in the presence of quenched disorder. [1] S. Diehl et al., Nature Physics 4, 878 - 883 (2008) [2] L. M. Sieberer et al., Phys. Rev. Lett. 110, 195301 [Preview Abstract] |
Thursday, June 8, 2017 2:12PM - 2:24PM |
P6.00002: Interaction-driven quantum phase transitions of Bose condensates in shaken optical lattices Logan W. Clark, Lei Feng, Anita Gaj, Brandon M. Anderson, K. Levin, Cheng Chin Shaken optical lattices enable exciting opportunities to study exotic quantum many-body phases in ultracold atomic gases. An intriguing example occurs when shaking a Bose condensate in an optical lattice causes its dispersion to acquire new minima at non-zero quasi-momenta. In this case the condensate can undergo a quantum phase transition after which atoms occupy the new minima. Repulsive interactions cause atoms with different momentum to segregate into spatially-separated domains. Here, we will discuss the much richer phenomena which are enabled by the interactions occurring during the shaking period. These subtle interaction effects can favor new quantum phases which break additional symmetries that are otherwise present in the Hamiltonian. [Preview Abstract] |
Thursday, June 8, 2017 2:24PM - 2:36PM |
P6.00003: Floquet topological insulator in an optical lattice with modulated lattice depth Yangqian Yan, Tony Lee We propose a simple scheme to realize a Floquet topological insulator in an optical lattice by weakly modulating the lattice depth. When the modulation frequency resonantly couples the s and p bands, the Floquet Hamiltonian becomes topologically nontrivial. We map out the topological transition as a function of frequency and amplitude. We also confirm the bulk topology by finding edge states in a lattice with open boundary conditions. An advantage of our scheme is that the modulation amplitude can be relatively small, so the heating can be minimal. [Preview Abstract] |
Thursday, June 8, 2017 2:36PM - 2:48PM |
P6.00004: Abstract Withdrawn
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Thursday, June 8, 2017 2:48PM - 3:00PM |
P6.00005: Parity-time symmetry breaking transitions in an ultracold Fermi gas with Floquet dissipation Le Luo, Jiaming Li, Andrew Harter, Leonardo de Melo, Yogesh Joglekar Open physical systems with balanced loss and gain exhibit a transition, absent in their solitary counterparts, which engenders modes that exponentially decay or grow with time and thus spontaneously breaks the parity-time ($\mathcal{PT}$) symmetry. This $\mathcal{PT}$-symmetry breaking is induced by increasing the strength of the loss and gain, but also occurs in a pure dissipative system without gain. Here we report on the first quantum version of $\mathcal{PT}$-symmetry breaking transitions using ultracold $^6$Li atoms. We simulate static and Floquet dissipative Hamiltonians by generating controlled, state-dependent atom loss in a noninteracting Fermi gas, and observe the $\mathcal{PT}$-symmetry breaking transitions by tracking the atom number for each state. In contrast to a single transition in the static case, the Floquet counterpart undergoes $\mathcal{PT}$-symmetry breaking and restoring transitions at vanishingly small dissipation strength. Our results show that Floquet dissipation is a versatile tool for navigating phases where the $\mathcal{PT}$-symmetry is either broken or conserved. The ultracold Fermi gas, with engineered Floquet dissipation, provides a starting point for exploring the interplay between interaction and dissipation effects in open quantum systems. [Preview Abstract] |
Thursday, June 8, 2017 3:00PM - 3:12PM |
P6.00006: Engineering topological defect patterns of Bose condensates in shaken optical lattices Lei Feng, Logan W. Clark, Anita Gaj, Cheng Chin Topological defects emerge and play an essential role in the dynamics of systems undergoing continuous, symmetry-breaking phase transitions. Here, we study the topological defects (domain walls) which form when a Bose condensate in a shaken optical lattice undergoes a quantum phase transition and separates into domains of superfluid with finite momentum. Here, we experimentally demonstrate the ability to control the pattern of domain walls using a digital micromirror device. We further explore implementations of this technique to study dynamics near the phase transition and the evolution of topological defects. [Preview Abstract] |
Thursday, June 8, 2017 3:12PM - 3:24PM |
P6.00007: Interaction quenched ultracold few-boson ensembles in periodically driven lattices Simeon Mistakidis, Peter Schmelcher The out-of-equilibrium dynamics of interaction quenched finite ultracold bosonic ensembles in periodically driven one-dimensional optical lattices is investigated. It is shown that periodic driving enforces the bosons in the outer wells of the finite lattice to exhibit out-of-phase dipole-like modes, while in the central well the atomic cloud experiences a local breathing mode. The dynamical behavior is investigated with varying driving frequency, revealing a resonant-like behavior of the intra-well dynamics. An interaction quench in the periodically driven lattice gives rise to admixtures of different excitations in the outer wells, an enhanced breathing in the center and an amplification of the tunneling dynamics. We observe then multiple resonances between the inter- and intra-well dynamics at different quench amplitudes, with the position of the resonances being tunable via the driving frequency. Our results pave the way for future investigations on the use of combined driving protocols in order to excite different inter- and intra-well modes and to subsequently control them. [Preview Abstract] |
Thursday, June 8, 2017 3:24PM - 3:36PM |
P6.00008: Lattice entanglement of ultracold atoms via lattice shaking Lushuai Cao, Xing Deng, Xue-Ting Fang, Qian-Ru Zhu, Zhong-Kun Hu Quantum entanglement of ultracold atoms is a key ingredient for quantum implementations, such as quantum computation. Ultracold atoms in optical lattices process various degrees of freedom (DOF) for generating entanglements, such as the site occupation, the orbital and the internal DOF, and the entanglement has been experimentally realized between the orbital and the internal DOF [Nature 527, 208], as well as between the site-occupation and internal DOF [Nature Physics 12, 783]. We propose a scheme to obtain entanglement between the orbital and the site-occupation DOF by lattice shaking. By carefully designing the shaking symmetry and taking advantage of the interaction blockade, this scheme can obtain entangled states on demand with controllable speed. [Preview Abstract] |
Thursday, June 8, 2017 3:36PM - 3:48PM |
P6.00009: An Acousto-Optical High Bandwidth Arbitrary Lattice Generator for $^{87}$Rb Z. S. Smith, M. E. W. Reed, A. Dewan, S. L Rolston We discuss the implementation and characterization of our high-bandwidth arbitrary lattice generator. The periods and phases of multiple simultaneous 1D lattices can be modulated, swept and jumped at MHz rates to produce both arbitrary time-averaged potentials and dressed-band Hamiltonians. A Mach-Zehnder interferometer spans the dynamic range of the lattice allowing its complete characterization and stabilization in-situ. We demonstrate both disordered and dressed band Hamiltonians. [Preview Abstract] |
Thursday, June 8, 2017 3:48PM - 4:00PM |
P6.00010: Quantized motion of Rydberg atoms in an amplitude-modulated lattice potential Vladimir Malinovsky, Kaitlin Moore, Andira Ramos, Georg Georg We present a model description of the spectroscopic line shape of Rydberg transitions in an amplitude-modulated Rydberg-atom lattice taking into account the quantization of the center-of-mass motion. In our model, the wave function of both ground and excited states are subject to the periodic potentials that arise from the optical-lattice fields. In contrast to other spectroscopic scheme, in our work the coupling (the effective Rabi frequency) is also periodic as function of the translational coordinate, and it is perfectly phase-locked to the lattice trapping potential. By solving the time-dependent Schr\"odinger equation in momentum representation we obtain the spectrum of the excited-state population. The numerical results for the momentum components of the ground and excited wave functions are averaged over the thermal momentum distribution of the Rydberg atoms. The effect of the lattice parameters and the interaction strength on the line shape of the Rydberg transitions is discussed. [Preview Abstract] |
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