Symmetry-Broken Many-Body Excited States of the Gaseous Atomic Double-Well Bose–Einstein Condensate

2019 ◽  
Vol 123 (10) ◽  
pp. 1962-1967
Author(s):  
David J. Masiello ◽  
William P. Reinhardt
Keyword(s):  
Excited States ◽  
Einstein Condensate ◽  
Many Body ◽  
Bose Einstein Condensate ◽  
Bose Einstein

scholarly journals Derivation of the Landau–Pekar Equations in a Many-Body Mean-Field Limit

2021 ◽  
Vol 240 (1) ◽  
pp. 383-417
Author(s):  
Nikolai Leopold ◽  
David Mitrouskas ◽  
Robert Seiringer
Keyword(s):  
Mean Field ◽  
Einstein Condensate ◽  
Back Reaction ◽  
Many Body ◽  
Field Limit ◽  
Mean Field Limit ◽  
Phonon Field ◽  
Bose Einstein Condensate ◽  
Weakly Couple ◽  
Bose Einstein

AbstractWe consider the Fröhlich Hamiltonian in a mean-field limit where many bosonic particles weakly couple to the quantized phonon field. For large particle numbers and a suitably small coupling, we show that the dynamics of the system is approximately described by the Landau–Pekar equations. These describe a Bose–Einstein condensate interacting with a classical polarization field, whose dynamics is effected by the condensate, i.e., the back-reaction of the phonons that are created by the particles during the time evolution is of leading order.

scholarly journals Nonperturbative dynamical many-body theory of a Bose-Einstein condensate

2005 ◽  
Vol 72 (6) ◽  
Author(s):  
Thomas Gasenzer ◽  
Jürgen Berges ◽  
Michael G. Schmidt ◽  
Marcos Seco
Keyword(s):  
Einstein Condensate ◽  
Many Body ◽  
Many Body Theory ◽  
Bose Einstein Condensate ◽  
Bose Einstein ◽  
Body Theory

scholarly journals Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Hiroyuki Tajima ◽  
Junichi Takahashi ◽  
Simeon Mistakidis ◽  
Eiji Nakano ◽  
Kei Iida
Keyword(s):  
Spectral Function ◽  
Einstein Condensate ◽  
Three Dimensions ◽  
Quantum Gas ◽  
Many Body ◽  
Bose Einstein Condensate ◽  
Spatial Dimensions ◽  
Three Body ◽  
Bose Einstein ◽  
The Impact

The notion of a polaron, originally introduced in the context of electrons in ionic lattices, helps us to understand how a quantum impurity behaves when being immersed in and interacting with a many-body background. We discuss the impact of the impurities on the medium particles by considering feedback effects from polarons that can be realized in ultracold quantum gas experiments. In particular, we exemplify the modifications of the medium in the presence of either Fermi or Bose polarons. Regarding Fermi polarons we present a corresponding many-body diagrammatic approach operating at finite temperatures and discuss how mediated two- and three-body interactions are implemented within this framework. Utilizing this approach, we analyze the behavior of the spectral function of Fermi polarons at finite temperature by varying impurity-medium interactions as well as spatial dimensions from three to one. Interestingly, we reveal that the spectral function of the medium atoms could be a useful quantity for analyzing the transition/crossover from attractive polarons to molecules in three-dimensions. As for the Bose polaron, we showcase the depletion of the background Bose-Einstein condensate in the vicinity of the impurity atom. Such spatial modulations would be important for future investigations regarding the quantification of interpolaron correlations in Bose polaron problems.

scholarly journals Entropy Production Within a Pulsed Bose–Einstein Condensate

2016 ◽  
Vol 71 (10) ◽  
pp. 875-881 ◽  
Author(s):  
Christoph Heinisch ◽  
Martin Holthaus
Keyword(s):  
Einstein Condensate ◽  
Many Body ◽  
Initial State ◽  
Site Model ◽  
Bose Einstein Condensate ◽  
Body Dynamics ◽  
Adiabatic Motion ◽  
The Many ◽  
Bose Einstein ◽  
Loss Of Coherence

AbstractWe suggest to subject anharmonically trapped Bose–Einstein condensates to sinusoidal forcing with a smooth, slowly changing envelope, and to measure the coherence of the system after such pulses. In a series of measurements with successively increased maximum forcing strength, one then expects an adiabatic return of the condensate to its initial state as long as the pulses remain sufficiently weak. In contrast, once the maximum driving amplitude exceeds a certain critical value there should be a drastic loss of coherence, reflecting significant heating induced by the pulse. This predicted experimental signature is traced to the loss of an effective adiabatic invariant, and to the ensuing breakdown of adiabatic motion of the system’s Floquet state when the many-body dynamics become chaotic. Our scenario is illustrated with the help of a two-site model of a forced bosonic Josephson junction, but should also hold for other, experimentally accessible configurations.

SEPARABILITY AND STABILITY OF SOLUTIONS OF THE 1-DIMENSIONAL NLSE WITH RESPECT TO EXTENSION INTO 2 AND 3 DIMENSIONS, AND TO INITIAL PERTURBATION BY WHITE NOISE

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1668-1671
Author(s):  
WILLIAM P. REINHARDT ◽  
MARY ANN LEUNG ◽  
LINCOLN D. CARR
Keyword(s):  
White Noise ◽  
Excited States ◽  
Initial Perturbation ◽  
Einstein Condensate ◽  
One Dimensional ◽  
Bose Einstein Condensate ◽  
Variable Step ◽  
Direct Numerical Integration ◽  
Bose Einstein ◽  
Pseudo Spectral

Stationary states of the nonlinear Schrödinger equation (NLSE) found analytically in previous work are extended into 2 and 3 dimensions by the simplest possible ansatz: namely, it is assumed that the direct product of one dimensional solutions for each dimension will yield a stationary state. The solutions considered mimic the dynamics of a repulsive Bose-Einstein condensate (BEC) in a trap of high aspect ratio. This assumption of separability, as established by direct numerical integration of the NLSE via variable step 4th order Runge-Kutta using a pseudo spectral basis, is found to work well for both ground and excited states for box transverse confinement, and for either box or periodic boundary conditions along the longest trap axis. Addition of white noise at t = 0, followed by similar numerical propagation in either 2 or 3 dimensions, is found to lead to instability once the transverse confining dimension are greater than approximately 6 healing lengths. Such instabilites eventually manifest themselves as vortices fathered by the well known snake instability of the NLSE solitons in dimensionalities higher than 1. The dynamics of interacting solitons may become chaotic as the solitons themselves become unstable in the presence of noise.

scholarly journals Many-body dissipative flow of a confined scalar Bose-Einstein condensate driven by a Gaussian impurity

2018 ◽  
Vol 98 (1) ◽  
Author(s):  
G. C. Katsimiga ◽  
S. I. Mistakidis ◽  
G. M. Koutentakis ◽  
P. G. Kevrekidis ◽  
P. Schmelcher
Keyword(s):  
Einstein Condensate ◽  
Many Body ◽  
Dissipative Flow ◽  
Bose Einstein Condensate ◽  
Bose Einstein

scholarly journals Anharmonicity-induced criticality of collective excitation in a trapped Bose–Einstein condensate

2018 ◽  
Vol 32 (31) ◽  
pp. 1850345
Author(s):  
Qun Wang ◽  
Bo Xiong
Keyword(s):  
Collective Mode ◽  
Collective Excitation ◽  
Einstein Condensate ◽  
Low Energy ◽  
Many Body ◽  
Bose Einstein Condensate ◽  
Large Numbers ◽  
Many Body Systems ◽  
Repulsive Forces ◽  
Bose Einstein

We investigate the low-energy excitations of a dilute atomic Bose gas confined in a anharmonic trap interacting with repulsive forces. The dispersion law of both surface and compression modes is derived and analyzed for large numbers of atoms in the trap, which show two branches of excitation and appear two critical values, where one of them indicates collective excitation which would be unstable dynamically, and the other one indicates the existing collective mode with lower frequency under anharmonic influence than that in harmonic trapping case. Our work reveals the key role played by the anharmonicity and interatomic forces which introduce a rich structure in the dynamic behavior of these new many-body systems.

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