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International Journal of Modern Physics B

Phase structure of binary Bose–Einstein condensates at finite temperature

Huu Phat Tran, Tuan Anh Nguyen, Viet Hoa Le, Thi Minh Hue Dang

Published Aug 24, 2016• 3 citations
Publisher

Abstract

The dynamical stability and its connection with phase structures of binary Bose–Einstein condensates (BECs) are systematically studied within framework of the Gross–Pitaevskii (GP) theory. We find that (a) the dynamical stability is the main factor governing both the symmetry breaking and the formation of various phases associated with the scenarios: symmetry restoration (SR) and inverse symmetry breaking (ISB); (b) the condensation of Bose gases might occur at constant temperature for chemical potentials varying in some definite regions. We suggest how to experimentally observe the foregoing phenomena whose possible existences in nature are theoretically confirmed.

DOI
10.1142/s0217979216501952

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The dynamical stability and its connection with phase structures of binary Bose–Einstein condensates (BECs) are systematically studied within framework of the Gross–Pitaevskii (GP) theory. We find that (a) the dynamical stability is the main factor governing both the symmetry breaking and the formation of various phases associated with the scenarios: symmetry restoration (SR) and inverse symmetry breaking (ISB); (b) the condensation of Bose gases might occur at constant temperature for chemical potentials varying in some definite regions. We suggest how to experimentally observe the foregoing phenomena whose possible existences in nature are theoretically confirmed.
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In this work, we study phase transitions in dilute Bose-Einstein Condensates theoretically. The Gross-Pitaevskii equation (GPE) is applied to describe the properties of dilute Bose gases near zero temperature for various confining geometries. Then, using the harmonic trap, the Thomas Fermi equation has been investigated. The Bose-Hubbard Model has been also investigated using the mean field approach. It is indicated that Bose-Einstein condensation is a second order phase transition. We also presented an exactly solvable phase transition model in which the phase transition is purely statistically derived. It is found out that the mean field theory can be applied to a number of physical systems so as to study the phenomena of Berezinsky-Kosterlitz- Thouless (BKT) phase transitions. Keywords : Phase Transition, BEC, GPE, Bose-Hubbard Model, Berezinsky-Kosterlitz-Thouless (BKT), Mean Field equation
The quantum phase transition in binary Bose Gases is studied using the Cornwall-Jackiw-Tomboulis effective potential approach in the double-bubble approximation, which preserves the Goldstone theorem. Its main feature is that the transition is second order occurring at ultra-cold temperatures associated with the type of inverse symmetry-breaking transition occurring when the chemical potential reaches a critical value. However, it cannot simultaneously occur for the two components of a binary mixture of Bose gases.