Quench dynamics and emergence of phase separation in two-component atomic Bose gases at zero temperature and above the Bose-Einstein-condensation critical temperature

摘要

We study the dynamics of two-component atomic Bose gases initially in a mixture encountering a suddennquench of the interspecies interactions. The dynamics above the critical temperature Tc is studied using anleading-order large-N approximation that predicted a phase transition from mixing to phase separation as anfunction of the interspecies coupling. Here, we explore the dynamics of this phase transition following a quenchnand compare our results to those found at zero temperature using the time-dependent Gross-Pitaevskii equationsnwhich ignore quantum and thermal fluctuations. In the regime above Tc where no condensate is present, however,nthe time evolution of the densities following the quench exhibits features similar to those found at zero temperaturenwhere only the condensates contribute to the densities.When the interspecies interaction jumps above the criticalnvalue, we observe dynamical transitions from a homogeneous mixture to a phase-separated structure for bothncases. Our simulations suggest that at temperatures above Tc where no condensate is present this dynamicalntransition should still be observable in experiments.