Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session K11: V: Cold Atoms and ComplexityVirtual Only
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Chair: Wenchao Ge, University of Rhode Island Room: Virtual Platform |
Wednesday, June 7, 2023 10:30AM - 10:42AM Withdrawn |
K11.00001: Building Krylov complexity from circuit complexity Ren Zhang, Chenwei Lv, Qi Zhou Krylov complexity has emerged as a new probe of operator growth in a wide range of non- |
Wednesday, June 7, 2023 10:42AM - 10:54AM |
K11.00002: Coupling of longitudinal and transversal fragmentations in the tunneling dynamics of Bose-Einstein condensates Anal Bhowmik, Ofir E Alon We propose a set-up to investigate tunneling dynamics of interacting bosons in the presence of coupling of longitudinal fragmentation, developed during the quantum dynamics, and transversal fragmentation, produced by the geometry of the trap. We find and explain how the coupling of fragmentations speeds up the collapse of density |
Wednesday, June 7, 2023 10:54AM - 11:06AM |
K11.00003: Breakup and fragmentation of a rotating Bose-Einstein condensate Sunayana Dutta, Axel U. J. Lode, Ofir E Alon The prime focus of research in the theoretical domain of rotating Bose-Einstein condensates is the emergence of quantum vortex states and condensed properties. However, this study looks at the other aspects by analyzing the impact of rotation on the ground state of interacting bosons trapped in anharmonic potentials. The multiconfigurational time-dependent Hartree method for bosons (MCTDHB), a well-known many-body method, is employed to explore the rotating condensate computed both at the mean-field and many-body levels. This study corroborates pathway of various degrees of fragmentation and subsequently breaking up of the ground state densities without ramping up any barrier in anharmonic potentials for strong rotation at the finite-particle limit. The breakup of density clouds is associated with angular momentum pumping in the condensate due to rotation. Interestingly, breaking of the densities computed at the mean-field and many-body levels depicts identical pattern both in the position and momentum space. The emergence of opposite anistropy in the variances despite having the same mean-field and many-body densities marks the presence of quantum fluctuations in the condensate. Finally, it is found that higher order symmetric systems, such as threefold and fourfold, in the rotating frame lead to an n-fold fragmented state while preserving the rotational symmetry of the condensate. |
Wednesday, June 7, 2023 11:06AM - 11:18AM |
K11.00004: Topological solitons of spinor Bose-Einstein condensate with spherical-shell geometry Chih-Chun Chien, Yan He A class of topological solitons, called the lumps, of three-component spinor Bose-Einstein condensate (BEC) is characterized when the BEC is placed on a spherical shell, which is made possible by recent progress in trapping ultracold atoms. The lump solitons are solutions to the nonlinear coupled equations from the minimization of the energy of the BEC. The topological properties of the lump solitons come from the homotopy between the real space, which is a two-sphere, and the order-parameter space from the vector fields formed by the three components of the spinor BEC, which is also a two-sphere. We define the winding number to count the wrapping between the two spaces and present an ansatz for generating the topological lump solitons with quantized winding numbers. The excitation energies of the lumps indicate that it is not energetically favorable for a high-winding lump to decay into multiple low-winding ones, in contrast to quantum vortices in superfluids. The lump solitons are realizable in spinor BEC and showcase the interplay between topology, nonlinear physics, and ultracold atoms. |
Wednesday, June 7, 2023 11:18AM - 11:30AM |
K11.00005: Theory of two-terminal transport through a lossy quantum point contact Shun Uchino Recently, the ETH group has succeeded in observing mesoscopic currents through a quantum point contact in the presence of particle loss [1]. Motivated by such an experimental progress, in this talk, I will discuss a mesoscopic transport theory to deal with the lossy quantum point contact. I will explain formulas associated with the mesoscopic currents [2], and unpublished works if time permits. |
Wednesday, June 7, 2023 11:30AM - 11:42AM |
K11.00006: Spin conductivity spectrum in ultracold atomic gases Yuta Sekino, Hiroyuki Tajima, Shun Uchino In this talk, we propose the method to measure frequency-dependent spin conductivity, which is elusive in solid-state materials [1]. Then, we present our theoretical analysis of the spin conductivity for several cold atomic systems in order to demonstrate that the spin conductivity spectrum becomes powerful probes to investigate many-body properteis of cold atoms. Indeed, the spin conductivity spectra includes physical information such as the Tomonaga-Luttinger parameter of spin in one-dimensional systems [1], topological phase transition in the 1D p-wave Fermi superfluid [2], and spin superfluidity in a binary Bose mixture [3]. |
Wednesday, June 7, 2023 11:42AM - 11:54AM |
K11.00007: Breakdown of the quantum adiabatic algorithm and its remedies in Rydberg atom arrays Benjamin Schiffer, Dominik S Wild, Nishad Maskara, Madelyn Cain, Mikhail D Lukin, Rhine Samajdar Classical optimization problems can be solved by adiabatically preparing the ground state of a quantum Hamiltonian that encodes the problem. The performance of this approach is determined by the smallest gap encountered during the evolution. In this work, we consider the maximum independent set problem, which can be naturally encoded in the Hamiltonian describing an array of neutral Rydberg atoms. We present a general construction of instances of the problem for which the minimum gap decays superexponentially with system size, implying a superexponentially large time to solution via adiabatic evolution. Local degeneracies can cause the system to initially evolve and localize into a configuration far from the solution in terms of Hamming distance. Such behavior can be independently induced by tails of the Rydberg interaction as well. We investigate remedies to this problem and observe that quenches in these models exhibit signatures of quantum many-body scars. By quenching from a suboptimal configuration, states with a large overlap with the ground state can be efficiently prepared, illustrating the utility of quantum quenches as an algorithmic tool. |
Wednesday, June 7, 2023 11:54AM - 12:06PM |
K11.00008: Optical lattices entering the realm of solid-state crystals Mohammadsadegh Khazali Optical lattices are the basic blocks of atomic quantum technology. The scale and resolution of these lattices are diffraction-limited to the light wavelength. Tight confinement of single sites in conventional lattices requires excessive laser intensity which in turn suppresses the coherence due to enhanced scattering. In this talk I propose a new scheme for atomic optical lattice with sub-wavelength spatial structure. The coherent optical control of Rydberg interaction has opened a wide range of applications in quantum technology [1-8]. This presentation utilises the nonlinear optical response of the three-level Rydberg-dressed atoms to form ultra-narrow trapping potentials [9]. This arrangement is not constrained by the diffraction limit of the driving fields. The lattice consists of a 3D array of ultra-narrow Lorentzian wells with sub-nanometer widths. The scheme allows moving adjacent sites to close distances with sub-nanometer resolution. These extreme scales are now optically accessible by a hybrid scheme deploying the dipolar interaction and optical twist of atomic eigenstates. The interaction-induced two-body resonance that forms the trapping potential [10], only occurs at a peculiar laser intensity, localizing the trap sites to ultra-narrow regions over the standing-wave driving field. The Lorentzian trapping potentials with 2A° width and 30MHz depth are realizable with scattering rates as low as 1Hz. The mentioned improvements allow quantum logic operations with Rydberg-Fermi interaction [11-12]. The new features are particularly demanding for the realization of atomtronics, quantum walks [13], Hubbard models, and neutral-atom quantum simulation. |
Wednesday, June 7, 2023 12:06PM - 12:18PM |
K11.00009: Dimensional Reduction in Quantum Optics Jannik Ströhle, Wolfgang P Schleich, Richard Lopp One-dimensional quantum optical models usually rest on the intuition of large scale separations associated with the different spatial dimensions, for example when studying quasi one-dimensional atomic motion, potentially resulting in the violation of 3+1D Maxwell's theory. Here, we present a rigorous foundation for this approximation by means of the light-matter interaction. We show how the quantized electromagnetic field can be decomposed - without approximation - into an infinite number of one-dimensional subfields when studying axially symmetric setups, such as a fiber cavity, a laser beam or a wave guide. The dimensional reduction approximation then corresponds to a truncation in the number of such subfields that in turn, when considering the interaction with for instance an atom, corresponds to an approximation to the atomic spatial profile. We explore under what conditions the standard dimensional reduction approximation of a single subfield is justified, and when corrections are necessary in order to account for the dynamics due to the neglected spatial dimensions. In particular we will examine what role vacuum fluctuations play in the validity of the approximation. |
Wednesday, June 7, 2023 12:18PM - 12:30PM |
K11.00010: Phonon-Polaritons via the Cavity Born-Oppenheimer Approximation Iman Ahmadabadi, John R Bonini, Johannes Flick Strong light-matter coupling in optical cavities can alter the dynamics of molecular and material systems resulting in polaritonic excitation spectra and modified reaction pathways. For strongly coupled photon modes close in energy to nuclear vibrations the Cavity Born Oppenheimer Approximation (CBOA) in the context of quantum-electrodynamical density functional theory (QEDFT) has been demonstrated to be an appropriate description of the coupled light-matter system. In this study, we present a theory based on CBOA to study the modification of vibrational modes in molecular and insulating solid systems by coupling to low frequency photon modes in optical cavities. Using a mapping of the CBOA energy functional (U) to a finite field enthalpy (F) based on the modern theory of polarization, we can utilize existing ab initio finite electric field methods to calculate the cavity modified phonon spectra in solids. Phonon-polariton modes are then obtained from the nuclear and photonic Hessian matrix. We show that this formalism can be generalized to multiple photon modes. |
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