Phase Diagram of Mixtures of Ultracold Bosons in Optical Lattice
S. Anufriiev and T.A. Zaleski
Institute of Low Temperature and Structure Research, PAS, Okólna 2, 50-422 Wrocław, Poland
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We study a behaviour of mixture of two species of ultracold bosons trapped in optical lattice. Using mean-field approximation, we determine the phase diagram of the system for wide range of parameters. We observe that each of the groups of atoms can condense into superfluid state or localize and form: the Mott insulator, which yields that the whole system is either superfluid, the Mott insulator, or a mixed state. It appears that introduction of interaction between different kinds of atoms can strongly renormalise the phase diagram. It can alter the critical behaviour modifying multi-criticality of crossing points and order of phase transitions between mixed and superfluid states.

DOI: 10.12693/APhysPolA.130.629
PACS numbers: 03.75.Hh, 05.30.Jp, 67.85.Hj