We examine the role of thermal fluctuations in uniform two-dimensional binary Bose mixtures of dilute ultracold atomic gases. We use a mean-field Hartree-Fock theory to derive analytical predictions for the miscible-immiscible transition. A nontrivial result of this theory is that a fully miscible phase at T=0 may become unstable at T≠0, as a consequence of a divergent behavior in the spin susceptibility. We test this prediction by performing numerical simulations with the stochastic (projected) Gross-Pitaevskii equation, which includes beyond mean-field effects. We calculate the equilibrium configurations at different temperatures and interaction strengths and we simulate spin oscillations produced by a weak external perturbation. Despite some qualitative agreement, the comparison between the two theories shows that the mean-field approximation is not able to properly describe the behavior of the two-dimensional mixture near the miscible-immiscible transition, as thermal fluctuations smoothen all sharp features both in the phase diagram and in spin dynamics, except for temperature well below the critical temperature for superfluidity.

Finite-temperature spin dynamics of a two-dimensional Bose-Bose atomic mixture / Roy, A.; Ota, M.; Recati, A.; Dalfovo, F.. - In: PHYSICAL REVIEW RESEARCH. - ISSN 2643-1564. - 3:1(2021). [10.1103/PhysRevResearch.3.013161]

Finite-temperature spin dynamics of a two-dimensional Bose-Bose atomic mixture

Roy A.;Ota M.;Recati A.;Dalfovo F.
2021-01-01

Abstract

We examine the role of thermal fluctuations in uniform two-dimensional binary Bose mixtures of dilute ultracold atomic gases. We use a mean-field Hartree-Fock theory to derive analytical predictions for the miscible-immiscible transition. A nontrivial result of this theory is that a fully miscible phase at T=0 may become unstable at T≠0, as a consequence of a divergent behavior in the spin susceptibility. We test this prediction by performing numerical simulations with the stochastic (projected) Gross-Pitaevskii equation, which includes beyond mean-field effects. We calculate the equilibrium configurations at different temperatures and interaction strengths and we simulate spin oscillations produced by a weak external perturbation. Despite some qualitative agreement, the comparison between the two theories shows that the mean-field approximation is not able to properly describe the behavior of the two-dimensional mixture near the miscible-immiscible transition, as thermal fluctuations smoothen all sharp features both in the phase diagram and in spin dynamics, except for temperature well below the critical temperature for superfluidity.
2021
1
Roy, A.; Ota, M.; Recati, A.; Dalfovo, F.
Finite-temperature spin dynamics of a two-dimensional Bose-Bose atomic mixture / Roy, A.; Ota, M.; Recati, A.; Dalfovo, F.. - In: PHYSICAL REVIEW RESEARCH. - ISSN 2643-1564. - 3:1(2021). [10.1103/PhysRevResearch.3.013161]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/337280
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