Bulletin of the American Physical Society
APS March Meeting 2021
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X27: Ultracold AtomsLive

Hide Abstracts 
Sponsoring Units: DAMOP Chair: Vito Scarola, Virginia Tech 
Friday, March 19, 2021 8:00AM  8:12AM Live 
X27.00001: Signatures of interband transitions on dynamical localization Sara Medhet, Tomotake Yamakoshi, Muhammad Ayub, Farhan Saif, Shinichi Watanabe We explain the dynamics of ultracold atoms in amplitude modulated optical lattice with harmonic confinement. We show the existence of dynamical localization that manifests itself as the cold atoms exhibit quantum suppression of classical chaos in the dynamical system. The exponential localization takes place both in momentum as well as in coordinate space within certain windows on modulation amplitude. We show that interband transitions, taking place due to the amplitude modulation in optical lattice, play an important role in controlling the dynamical localization of matter waves. Our obtained results can be generalized to other dynamical systems and are experimentally realizable as we consider the values of parameters from the presentday available experiments. 
Friday, March 19, 2021 8:12AM  8:24AM Live 
X27.00002: Composite particles with minimum uncertainty in spacetime Carolyn E Wood, Magdalena Zych Composite particles such as atoms and molecules are promising tools for future experiments testing fundamental physics. However, as experiments advance in complexity and precision, the loss of spatial coherence is a problem which will only increase. In all theoretical studies of propagating composite particles, their internal energy components delocalise, and their spatial coherence is destroyed. This calls into question the suitability of composite particles as experimental tools, and is contrary to our understanding of atoms and molecules as cohesive entities with welllocalised spacetime trajectories. 
Friday, March 19, 2021 8:24AM  8:36AM Live 
X27.00003: Creation of 2000atom GreenbergerHorneZeilinger states by entanglement amplification Yajuan Zhao, Rui Zhang, Wenlan Chen, XiangBin Wang, Jiazhong Hu We propose an entanglementcreation scheme in a multiatom ensemble trapped in an optical cavity, named entanglement amplification, converting unentangled states into entangled states and amplifying lessentangled ones to maximallyentangled GreenbergerHorneZeilinger (GHZ) states whose fidelity is logarithmically depending on the atom number and robust against common experimental noises. The scheme starts with a multiatom ensemble initialized in a coherent spin state. By shifting the energy of a particular Dicke state, we break the Hilbert space of the ensemble into two isolated subspaces to tear the coherent spin state into two components so that entanglement is introduced. After that, we utilize the isolated subspaces to further enhance the entanglement by coherently separating the two components. By singleparticle Rabi drivings on atoms in a highfinesse optical cavity illuminated by a singlefrequency light, 2000atom GHZ states can be created with a fidelity above 80% in an experimentally achievable system, making resources of ensembles at Heisenberg limit practically available for quantum metrology. 
Friday, March 19, 2021 8:36AM  8:48AM Live 
X27.00004: New physical concepts: Fermionic Exchange Force and BoseEinstein Force Christian Schilling, Carlos BenavidesRiveros, Julia Liebert, Rolf Schilling The particleexchange symmetry has a strong influence on the behavior and the properties of systems of N identical particles. While fermionic occupation numbers are restricted according to Pauli's exclusion principle, 0 ≦ n_{k} ≦ 1, bosonic occupation numbers can take arbitrary values 0 ≦ n_{k} ≦ N. It is also a matter of fact, however, that occupation numbers in realistic systems of interacting fermions and bosons can never attain the maximal possible value, i.e., 1 and N, respectively. By resorting to oneparticle reduced density matrix functional theory we provide an explanation for this [1,2]: The gradient of the exact functional diverges repulsively whenever an occupation number n_{k} tends to attain the maximal value. In that sense we provide in particular a fundamental and quantitative explanation for the absence of complete BoseEinstein condensation (as characterized by n_{k}=N) in nature [2]. These new concepts are universal in the sense that the fermionic exchange force and the BoseEinstein force are present in all systems regardless of the particle number N, the spatial dimensionality and the interaction potentials. 
Friday, March 19, 2021 8:48AM  9:00AM Live 
X27.00005: Dynamical crossover in the transient quench dynamics of shortrange transversefield Ising models Ceren Dag, Kai Sun In this work, we follow up on a recent numerical demonstration where outoftimeorder correlators (OTOC) of a singlesite are shown to exhibit typeI dynamical phase transition (DPTI) for (non)integrable shortrange transversefield Ising model (TFIM). Given the requirement of sophisticated probe techniques to measure OTOC, we ask whether simpler singlesite probes could be constructed to detect quantum phase transitions (QPT), e.g. magnetization per site. Because magnetization for shortrange TFIM cannot exhibit DPTI when quenched from polarized states, we question whether the transient regime could encode information about the underlying QPT. Decay rates of singlesite observables exhibit a cusplike feature which separates two dynamical phases, ordered and disordered, both of which have distinct nonequilibrium responses. We construct a dynamical order parameterlike quantity that exhibits a scaling law at the vicinity of the cusp. These signatures suggest a crossover that is originated from the underlying QPT and encoded into the transient regime of onepoint observables in shortrange TFIM. When integrability is strongly broken, the crossover boundary turns into a region that separates two other dynamical regions that act like dynamicallyordered and disordered phases. 
Friday, March 19, 2021 9:00AM  9:12AM Live 
X27.00006: Functional Theory for BoseEinstein Condensates and Origin of Quantum Depletion Julia Liebert, Christian Schilling Oneparticle reduced density matrix functional theory would potentially be the ideal approach for describing BoseEinstein condensates. It namely replaces the macroscopically complex wavefunction by the simple oneparticle reduced density matrix, therefore provides direct access to the degree of condensation and still recovers quantum correlations in an exact manner. We eventually initiate and establish this novel theory by deriving the respective universal functional F for general homogeneous BoseEinstein condensates with arbitrary pair interaction. Most importantly, the successful derivation necessitates a particlenumber conserving modification of Bogoliubov theory and a solution of the common phase dilemma of functional theories. We then illustrate this novel approach in several bosonic systems such as homogeneous Bose gases and the BoseHubbard model. Remarkably, the general form of F reveals the existence of a universal BoseEinstein condensation force. This generalization of the Fermi degeneracy pressure to interacting bosonic quantum systems of arbitrary size provides an alternative and more fundamental explanation for quantum depletion. 
Friday, March 19, 2021 9:12AM  9:24AM Live 
X27.00007: Multiphoton resonance and chiral transport in the generalized Rabi model Kwok Wai Ma The generalized Rabi model (gRM) with both onephoton and twophoton coupling terms has been successfully implemented in circuit quantum electrodynamics systems. In this work, we examine theoretically multiphoton resonances in the gRM and derive their effective Hamiltonians. With different detunings in the system, we show that all three to sixphoton resonances can be achieved by involving two intermediate states. Furthermore, we study the interplay between multiphoton resonance and chiral transport of photon Fock states in a resonator junction with broken timereversal symmetry. Depending on the qubitphoton interaction and photonhopping amplitude, we find that the system can demonstrate different shorttime dynamics. 
Friday, March 19, 2021 9:24AM  9:36AM Live 
X27.00008: Reconfigurable directional Raman amplifier controlled by the internal state of cold atoms chirally coupled to a nanophotonic waveguide Sebastian Pucher, Christian Liedl, Shuwei Jin, Arno Rauschenbeutel, Philipp Schneeweiss We experimentally demonstrate a scheme for nonreciprocal amplification of light, which uses atoms that are chirally coupled to a nanophotonic waveguide. Rather than a magnetic field, in this scheme, it is the atomic spin that breaks Lorentz reciprocity [1]. Specifically, we show directional amplification of guided light using cold cesium atoms coupled to the evanescent field surrounding an optical nanofiber. By preparing the atoms in different Zeeman states of the ground state manifold, we can control the direction in which amplification occurs. We observe an exponential increase of the optical output power with the number of atoms and obtain up to 50 % singlepass gain for about 2000 atoms. Our results contribute to establishing a new class of spincontrolled, nonreciprocal integrated optical devices. 
Friday, March 19, 2021 9:36AM  9:48AM Live 
X27.00009: Detecting fractional Chern insulators in optical lattices through quantized displacement Johannes Motruk, Ilyoun Na The realization of interacting topological states of matter such as fractional Chern insulators (FCIs) in cold atom systems has recently come within experimental reach due to the high controllability of optical lattices and the engineering of topological band structures with the help of synthetic gauge fields. However, their detection might prove difficult since transport measurements akin to those in solid state systems are challenging to perform in cold atom setups. We show that for a ν=1/2 FCI state realized in the lowest band of a HarperHofstadter model of interacting bosons confined by a harmonic trapping potential, the fractionally quantized Hall conductivity σ_{xy} can be accurately determined by the displacement of the atomic cloud under the action of a constant force. This provides an experimentally realistic measurable signal to detect the topological nature of the state. Using matrixproduct state algorithms, we demonstrate that in both cylinder and square geometries, the movement of the particle cloud in time under the application of a constant force field on top of the confining potential is proportional to σ_{xy} and determine the suitable range of field strengths. 
Friday, March 19, 2021 9:48AM  10:00AM Live 
X27.00010: Measurementinduced entanglement transitions in freefermion models Joseph Merritt There has been recent activity on the entanglement dynamics under random unitary evolution and projective measurements in one dimensional quantum systems. Using Majorana operators, we can study this phenomenon with freefermion unitary dynamics. For certain choices of unitary evolution, namely those which swap neighboring Majorana operators, we map the evolution to the statistical model of completely packed loops with crossings and study the corresponding phase diagram. This diagram exhibits a transition from an area law to a critical Goldstone phase with a logarithmic entropy scaling law. We generalize this model using the language of Fermionic Gaussian states to a general free fermion unitary evolution acting on neighboring Majorana operators, and numerically compute its phase diagram as well. We find that the phase transition persists, but the transition line occurs at a different location in the diagram. 
Friday, March 19, 2021 10:00AM  10:12AM Live 
X27.00011: An Estimation of the Isotope Shift and Hyperfine Splitting in the 6s 3/2 [3/2]_{2} and 6p 3/2 [5/2]_{3} States in ^{129m}Xe, ^{131m}Xe, ^{133}Xe, ^{133m}Xe, ^{135}Xe Jacob DeLange, Michael K Shaffer, Randall J Knize The leading candidates for remote detection of nuclear activity are Xe and its isotopes, particularly ^{131m}Xe, ^{133}Xe,^{ 133m}Xe, and ^{135}Xe. In the past decade, a technology has emerged that is capable of separating and counting rare gas radioisotopes at sensitivities of 10^{16} using laser cooling and a MagnetoOptical Trap called Atom Trap Trace Analysis (ATTA). This technique takes advantage of a cycling transition within the electronic energy level structure of Xe which varies between its isotopes. This variation, which gives ATTA greater selectivity than existing detection methods, is caused by changes in isotope mass, nuclear charge distribution, and nuclear spin. While the spectra for the stable isotopes of Xe on this transition have been documented, they are unknown for the radioisotopes of interest. For the ATTA system to quantify their abundance, their energy level shifts and splittings must be experimentally determined. These measurements are one goal of this ongoing research, however given the cost of obtaining these isotopes, it is desirable to have an estimate to guide the spectroscopy, which is the subject here. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700