Finite-temperature spin dynamics of a two-dimensional Bose-Bose atomic mixture
Authors: Roy A., Ota M., Recati A., Dalfovo F.
Autors Affiliation: INO-CNR BEC Center, Universita di Trento, via Sommarive 14, Trento, I-38123, Italy; Trento Institute for Fundamental Physics and Applications, INFN, Povo, 38123, Italy
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.
Journal/Review: PHYSICAL REVIEW RESEARCH
Volume: 3 (1) Pages from: 013161-1 to: 013161-12
More Information: We are grateful to Stefano Giorgini and Sandro Stringari for many fruitful discussions concerning the results reported in Sec. II. We also thank Nick Keepfer for insightful discussions related to SGPE. A. Roy thanks S. Gautam for useful discussions. This work is supported by Provincia Autonoma di Trento and from INFN-TIFPA under the project FIS overline h. A. Recati acknowledges support from the ItalianMIUR under the PRIN2017 project CEnTraL (Protocol No. 20172H2SC4). We acknowledge the CINECA award under the ISCRA initiative, for the availability of high performance computing resources and support. This material is based upon work supported with GCP research credits by Google Cloud.KeyWords: gases; superfluid; bosons; coldDOI: 10.1103/PhysRevResearch.3.013161