Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session E26: BoseEinstein Condensates and Nonlinear Waves 
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Sponsoring Units: DAMOP Chair: Mark Edwards, Georgia Southern University Room: LACC 404A 
Tuesday, March 6, 2018 8:00AM  8:12AM 
E26.00001: Photon thermalization and Bose condensation via laser cooling of atoms ChiaoHsuan Wang, Michael Gullans, James Porto, William Phillips, Jacob Taylor The advent of laser cooling and trapping techniques for neutral atoms has led to remarkable breakthroughs in exploring the interaction between light and matter at ultracold temperatures. Here we focus on laser cooling from the perspective of the light  specifically, the scattering of light between different optical modes in the presence of the cooling beams. In high optical depth atomic ensembles, we show that photons reemitted during the laser cooling process can equilibrate with the atomic motion and reach a steady state, and a grand canonical ensemble of photons can arise directly via atomic laser cooling in an experimentally accessible regime, with a chemical potential controlled by the laser frequency. Moreover, by placing the atoms in a curved cavity, the transverse modes in the cavity can be mapped into 2D massive bosons inside a parabolic well and can lead to 2D BoseEinstein condensate of light. We consider realization of this regime using twolevel atoms in Doppler cooling, and construct a phase diagram in the laser frequency and intensity parameter space showing the gain, condensate, thermal and quasithermal regimes for cavity photons with simulated values appropriate for the Yb intercombination transition. 
Tuesday, March 6, 2018 8:12AM  8:24AM 
E26.00002: Bose–Einstein condensation and superfluidity of trapped photons with coordinatedependent mass and interactions Oleg Berman, Roman Kezerashvili, Yurii Lozovik The condensate density profile of trapped twodimensional gas of photons in an optical microcavity, filled by a dye solution, is obtained by taking into account coordinate dependence effective mass of cavity photons and photon–photon coupling parameter [1]. The profiles for the densities of the superfluid and normal phases of trapped photons in the different regions of the system at the fixed temperature are analyzed. The radial dependencies of local meanfield phase transition temperature and local KosterlitzThouless transition temperature of superfluidity for trapped microcavity photons are demonstrated. The coordinate dependence of cavity photon effective mass and photon–photon coupling parameter is important for the mirrors of smaller radius with the high trapping frequency, which provides BoseEinstein condensation and superfluidity for smaller critical number of photons at the same temperature. We discuss a possibility of an experimental study of the density profiles for the normal and superfluid components in the system under consideration. 
Tuesday, March 6, 2018 8:24AM  8:36AM 
E26.00003: TransPlanckian issues and Emergent Gravity: from BoseEinstein condensates (BEC) to analogue black holes Supratik Sarkar, A. Bhattacharyay To account for the nonlocal interactions in a BoseEinstein Condensate (BEC), an addition of a minimal correction term to the standard GrossPitaevskii model effectively can make the healing length (ξ) decrease more rapidly with the increase of swave scattering length (a). From analogue gravity perspectives, this shrinking of ξ via tuning a through Feshbach resonance, in principle, makes the shortwavelength (i.e. high energy) regime more accessible experimentally by pushing the Lorentzbreaking dispersion even more towards the UV side. The effects of the Lorentzbreaking quantum potential term in the BECdynamics on independent multiple scales can be captured through a UVIR coupling of the phononexcitationmodes of a massive minimally coupled KleinGordon field. The analysis was argued on a (3+1)D flat spacetime. The analysis is extended for a canonical acoustic black hole in a (3+1)D curved spacetime through presenting an analogue gravity model upto order(ξ^{2}) accuracy. In our formalism, the growth rate of the largewavelength secondary ω modes is found to hold the clue to extract the lost information regarding the shortwavelength primary ω_{1} modes. So this can actually reveal the relative abundance of the originally Hawking radiated quanta in a (3+1)D curved background. 
Tuesday, March 6, 2018 8:36AM  8:48AM 
E26.00004: Localized Horizon Modes Partnered to Acoustic Hawking Emission in a BoseEinstein Condensate Jonathan Curtis, Gil Refael, Victor Galitski We consider a superfluid condensate with a quasionedimensional flow possessing an acoustic event horizon. In addition to the production of sonic Hawking radiation we find components of the eigenmodes which are localized onto the exterior of the sonic blackhole. The physical significance of these localized modes is discussed, with a particular emphasis on how they may affect the entanglement structure and information capacity of the sonic blackhole. 
Tuesday, March 6, 2018 8:48AM  9:00AM 
E26.00005: Ondemand Smooth Flow by Stirring a Racetrack Atom Circuit Olatunde Oladehin, Benjamin Eller, Charles Clark, Mark Edwards We studied how smooth flow can be produced by stirring an ultracold atom circuit consisting of a gaseous BoseEinstein condensate (BEC) confined in a ``racetrack'' potential. We assume that the BEC is strongly confined in a horizontal plane by a vertical harmonic trap and, within this plane, subjected to an arbitrary twodimensional potential using laser light. The racetrack potential is made up of two straight parallel channels of length L connected on both ends by semicircular channels of the same width and (energy) depth as the straightaways. We used the GrossPitaevskii equation (GPE) to simulate the behavior of the BEC in this potential when stirred by a rectangular paddle at various speeds and barrier heights. For fixed L we stirred the BEC at four different speeds and with barrier heights that varied from 0.5μ to 2.0μ. This series of conditions was performed for seven different values of L. We also devised a simple 1D model of the stirring of the BEC based on the GPE in order to understand how smooth flow is produced by stirring. This understanding should enable the design of a stirring sequence that would produce a given flow on demand. 
Tuesday, March 6, 2018 9:00AM  9:12AM 
E26.00006: Finitetemperature Effects on Producing Smooth Flow in a Racetrack Atom Circuit Benjamin Eller, Olatunde Oladehin, Charles Clark, Mark Edwards We studied smooth flow produced by stirring an ultracold atom circuit consisting of a gaseous BoseEinstein condensate (BEC) confined in a ``racetrack'' potential at finite temperature. The BEC is assumed to be strongly confined in a horizontal plane by a vertical harmonic trap and, within this plane, subjected to an arbitrary twodimensional potential. The racetrack potential is made up of two straight parallel channels connected on both ends by semicircular channels of the same width and (energy) depth as the straightaways. We used the ZarembaNikuniGriffin model to simulate the behavior of the BEC and noncondensate in this potential when stirred by a rectangular paddle at various speeds and barrier heights. We compare the amount of flow produced by stirring under these conditions with the flow produced under the same conditions but at zero temperature. We discuss how a simple model which predicts the flow produced by stirring at zero temperature could be modified for finite temperature. 
Tuesday, March 6, 2018 9:12AM  9:24AM 
E26.00007: Nonlinear Band Spectrum and Elementary Excitations of a Bose Gas Within a MultiRods Structure Omar Rodriguez Lopez, Miguel Solis We calculate the ground state (gs) energy spectrum as well as the elementary excitations of a 
Tuesday, March 6, 2018 9:24AM  9:36AM 
E26.00008: Absence of Landau damping in driven threecomponent BoseEinstein condensate in optical lattices Gavril Shchedrin, Daniel Jaschke, Lincoln Carr Multicomponent BoseEinstein condensates (BECs) are a unique form of matter that allow one to explore coherent manybody phenomena in a macroscopic quantum system by manipulating its internal degrees of freedom. The ground state of alkalibased BECs, which includes $^{7}{\rm Li}$, $^{23}{\rm Na}$, and $^{87}{\rm Rb}$, is characterized by the hyperfine spin $F$, that can be best probed in optical lattices, which liberate its $2F+1$ internal components and thus provides a direct access to its internal structure. We explore the quantum manybody physics of a threecomponent BoseEinstein condensate in optical lattices driven by laser fields in $V$ and $\Lambda$ configurations. We obtain exact analytical expressions for the energy spectrum and amplitudes of elementary excitations, and discover symmetries among them. We demonstrate that the applied laser fields induce a gap in the otherwise gapless Bogoliubov spectrum. We find that Landau damping of the collective modes above the energy of the gap is carried by laserinduced roton modes and is considerably suppressed compared to the phononmediated damping endemic to undriven scalar condensates. 
Tuesday, March 6, 2018 9:36AM  9:48AM 
E26.00009: Collective excitations of unconventional twospecies BoseEinstein condensation in the porbital bands of twodimensional hybrid optical lattices IKang Liu, ShihChuan Gou Unconventional BoseEinstein condensation (BEC) arising in the metastable high orbital states of a quantum manybody system has been a topical subject in the recent years [14]. Based on a modified imaginarytime propagation method in momentum space, we had previously investigated the unconventional BEC in the twospecies mixture with pwave symmetry in the second band of a bipartite optical lattice [13,5], and shown that such a system undergoes a phase transition from a complex staggeredorbital state to a real checkerboardlike spindensity state when the strength of interspecies interaction overtakes its intraspecies counterpart. In this presentation, we follow up to study the stability of such unconventional BEC state in the bipartite square lattice and a hybrid square lattice [6] by looking into the properties of its collective excitations which are obtained by numerically solving the BogoliubovdeGenne equation. 
Tuesday, March 6, 2018 9:48AM  10:00AM 
E26.00010: Splitting instability of a doubly quantized vortex in homogeneous superfluids Hiromitsu Takeuchi, Michikazu Kobayashi, Kenichi Kasamatsu We revisit the fundamental problem of splitting instability of a doublyquantized 
Tuesday, March 6, 2018 10:00AM  10:12AM 
E26.00011: Vortex lattices with multiple fluxes per unit cell in fast rotating dipolar BoseEinstein condensates SzuCheng Cheng, ShihDa Jheng A recently proposed wave function of vortex lattice, named as von Neumann lattice [1], is applied to examine the phases of vortex lattices in fast rotating dipolar BoseEinstein condensates. The von Neumann lattice is a general vortexlattice configuration which not only contains the Abrikosov lattice as a special case, but also bubble crystals [2] predicted numerically in the system. We applied von Neumann lattices to reexamine the vortexlattice phases in fast rotating dipolar BoseEinstein condensates. We find that vortex lattices with multiple fluxes per unit cell can be energetically stable inside the unstable regime predicted by vortex lattices with a single flux per unit cell [3]. 
Tuesday, March 6, 2018 10:12AM  10:24AM 
E26.00012: SU(3) gauge field theory of spin1 BoseEinstein condensates Emi Yukawa, Masahito Ueda We reformulate hydrodynamic theory of spin1 BoseEinstein condensates (BEC) in terms of an SU(3) gauge field and describe the meanfield dynamics equivalent to the multicomponent GrossPitaevskii equations. In this theory, the spin vector and the nematic tensor constitute a single ninecomponent tensor which serves as an SU(3) gauge field and describes the spinnematic texture in space and time. The constraints among the SU(3) gauge field imply the invariance of effective gauge potentials which encapsulate all effects of physical quantities and external fields. Compared with hydrodynamic theory, this new formulation greatly simplifies constraints on the gauge field and makes the derivation of hydrodynamic equations physically transparent. 
Tuesday, March 6, 2018 10:24AM  10:36AM 
E26.00013: Infinite lattice of vortex molecules Beinat Mencia Uranga, Austen Lamacraft We study the ground state of a 2D rotating two component BEC in the presence of an external electromagnetic field that gives rise to Rabi oscillations in between the two components. The EM field works as a confinement mechanism of vortices leading to the formation of vortex molecules: pairs of vortices, one of each component. We study the fullblown problem by solving the GrossPitaevskii equation for an infinite system. We explain the result in terms of an effective theory of electric dipoles with 2D dipolar interactions. 
Tuesday, March 6, 2018 10:36AM  10:48AM 
E26.00014: HugenholtzPines theorem for Bose–Einstein condensates with internal degrees of freedom Shohei Watabe The HugenholtzPines theorem for the spinf spinor BEC with broken U(1)×SO(3) symmetry is an unsolved problem in the field of ultracold quantum gases since 1998 when the experiment of the spin1 BEC was first realized, and its Bogoliubov theories were first proposed. In this presentation, we will propose the HugenholtzPines theorem for BECs with internal degrees of freedom. In order to that, we clarified the generalized version of the HugenholtzPines theorem for BECs with broken U(1)×SO(N) or U(1)×SU(N) symmetry in the presence of the SO(N) or SU(N) symmetry breaking external fields. This theorem serves to deductively organize the HugenhotlzPines theorem for spinf spinor BECs in the presence of an external magnetic field. We will introduce some specific results of the HugenholtzPines theorem in certain phases of the spin1 or spin2 BEC. 
Tuesday, March 6, 2018 10:48AM  11:00AM 
E26.00015: BoseEinstein condensation of a nonideal Bose gas of atoms with large spin Andrei Pavlov, Vladimir Babichenko, Ilya Polishchuk

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