2015/03/18 by Peder N. Galteland, Egor Babaev, Galteland, Peder N. +3
Physics and Astronomy · #FOS: Physical sciences #Quantum Gases (cond-mat.quant-gas) #cond-mat.quant-gas
paper · pdf · doi:10.48550/arxiv.1503.05583
13 pages, 12 figures, 41 references. Submitted to Physical Review
arxiv created 2015/03/18 · arxiv updated 2015/03/20
We consider a two-component immiscible Bose-Einstein condensate with dominating intra-species repulsive density-density interactions. In the ground-state phase of such a system only one condensates is present. This can be viewed as a spontaneous breakdown of ℤ2 symmetry. We study the phase diagram of the system at finite temperature beyond mean-field approximation. In the absence of rotation, we show that the system undergoes a first order phase transition from this ground state to a miscible two-component normal fluid as temperature is increased. In the presence of rotation, the system features a competition between vortex-vortex interaction and short range density-density interactions. This leads to a rotation-driven "mixing" phase transition in a spatially inhomogeneous state with additional broken U(1) symmetry. Thermal fluctuations in this state lead to nematic two-component sheets of vortex liquids. At sufficiently strong inter-component interaction, we find that the superfluid and ℤ2 phase transitions split. This results in the formation of an intermediate state which breaks only ℤ2 symmetry. It represents two phase separated normal fluids with density imbalance.