Ground-state phase diagram of spin-(1/2) bosons in a two-dimensional optical lattice

We study a two-species bosonic Hubbard model on a two-dimensional square lattice by means of quantum Monte Carlo simulations. In addition to the usual contact repulsive interactions between the particles, the Hamiltonian has an interconversion term which allows the transformation of two particles fr...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2011-08, Vol.84 (6)
Main Authors: Forges de Parny, L. de, Hebert, F., Rousseau, V. G., Scalettar, R. T., Batrouni, G. G., Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3 Singapore 117542
Format: Article
Language:English
Subjects:
ANGULAR MOMENTUM
BOSONS
CALCULATION METHODS
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPUTERIZED SIMULATION
CRYSTAL LATTICES
CRYSTAL MODELS
CRYSTAL STRUCTURE
DIAGRAMS
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
GROUND STATES
HAMILTONIANS
HUBBARD MODEL
INFORMATION
INTERACTIONS
INTERFERENCE
LASER RADIATION
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
MONTE CARLO METHOD
PARTICLE PROPERTIES
PHASE DIAGRAMS
POLARIZATION
QUANTUM OPERATORS
RADIATIONS
SIMULATION
SOLIDS
SPIN
STARK EFFECT
SUPERFLUIDITY
TETRAGONAL LATTICES
TWO-DIMENSIONAL CALCULATIONS
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Summary:We study a two-species bosonic Hubbard model on a two-dimensional square lattice by means of quantum Monte Carlo simulations. In addition to the usual contact repulsive interactions between the particles, the Hamiltonian has an interconversion term which allows the transformation of two particles from one species to the other. The phases are characterized by their solid or superfluid properties and by their polarization, i.e., the difference in the populations. When interspecies interactions are smaller than the intraspecies ones, the system is unpolarized, whereas in the opposite case the system is unpolarized in even Mott insulator lobes and polarized in odd Mott lobes and also in the superfluid phase. We show that in the latter case the transition between the Mott insulator of total density 2 and the superfluid can be of either second or first order depending on the relative values of the interactions, whereas the transitions are continuous in all other cases.
ISSN:1098-0121
1550-235X
DOI:10.1103/PHYSREVB.84.064529