Superfluid-insulator transitions of two-species Bosons in an optical lattice

Isacsson, A. ; Cha, Min-Chul ; Sengupta, K. ; Girvin, S. M. (2005) Superfluid-insulator transitions of two-species Bosons in an optical lattice Physical Review B: Condensed Matter and Materials Physics, 72 (18). 184507_1-184507_12. ISSN 1098-0121

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We consider the two-species bosonic Hubbard model with variable interspecies interaction and hopping strength in the grand canonical ensemble with a common chemical potential. We analyze the superfluid-insulator (SI) transition for the relevant parameter regimes and compute the ground state phase diagram in the vicinity of odd filling Mott states. We find that the superfluid-insulator transition occurs with (a) simultaneous onset of superfluidity of both species or (b) coexistence of Mott insulating state of one species and superfluidity of the other or, in the case of unit filling, (c) complete depopulation of one species. The superfluid-insulator transition can be first order in a large region of the phase diagram. We develop a variational mean-field method which takes into account the effect of second order quantum fluctuations on the superfluid-insulator transition and corroborate the mean-field phase diagram using a quantum Monte Carlo study.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:81311
Deposited On:06 Feb 2012 05:07
Last Modified:18 May 2016 22:55

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