Dispersion relations and self-localization of quasiparticles in coupled elongated Bose-Einstein condensates

Abstract

We present a detailed study of the spectrum and dispersion of Bogoliubov quasiparticles in two coupled elongated Bose-Einstein condensates. We develop an analytically solvable model that approximates two infinite homogeneous condensates and compare its predictions to a numerical simulation of a realistic trapped system. While the comparisons show a reasonable agreement between the two models, they also manifest the existence of several anomalous Bogoliubov modes in the spectrum. These modes show degeneracy in both energy and momentum together with self-localization in the coordinate space.

Superfluidity breakdown of Rabi-coupled two-component Bose-Einstein condensates in optical lattices

“…In the long-wavelength limit, the system can be approximately described by the twocoupled spatially homogeneous BEC with dressed mass m * . For a two-coupled homogeneous BEC, it has been analytically uncovered that the lowest collective excitation branch is independent of Ω and the Landau critical velocity is v L = (g + g 12 )n/(m * ) where n is the atomic density [42,51]. We approximate the density by an average density n = 0.5 from the nonlinear Bloch states shown in Fig.…”

“…There is a competition between interactions and the Rabi coupling. The Rabi-coupled twocomponent BECs represent active platforms for exploring nonlinear phenomena [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. In recent experiments, the Rabi coupling is accompanied by the generation of artificial spin-orbit coupling [52].…”

Dynamics of thermalization of two tunnel-coupled one-dimensional quasicondensates

“…In this paper, we study a simple example of such a setting-a pair of tunnel-coupled one-dimensional (1D) Bose gases in the quasicondensate regime. This system has already been studied extensively, both theoretically [8][9][10][11][12][13][14] and experimentally [15][16][17][18][19][20][21][22], in the scenario in which an initially single 1D quasicondensate was coherently split into two quasicondensates and allowed to relax through dephasing. In particular, in the experiment of Hofferberth et al [15], the authors observed a fast, subexponential decay of relative coherence in the completely decoupled case [23,24]; the dephasing between the two quasicondensate occurred on the order of milliseconds.…”