Commensurate two-component bosons in an optical lattice: ground state phase diagram.
Two sorts of bosons in an optical lattice at commensurate filling factors can form five stable super-fluid and insulating ground states with rich and nontrivial phase diagram. The structure of the ground state diagram is established by mapping a d-dimensional quantum system onto a (d+1)-dimensional classical loop-current model and Monte Carlo (MC) simulations of the latter. Surprisingly, the quantum phase diagram features, besides second-order lines, first-order transitions and two multicritical points. We explain why first-order transitions are generic for models with pairing interactions using microscopic and mean-field (MF) arguments. In some cases, the MC results strongly deviate from the MF predictions.
Kuklov
Anatoly
A
Department of Engineering Science and Physics, The College of Staten Island, City University of New York, Staten Island, New York 10314, USA.
Prokof'ev
Nikolay
N
Svistunov
Boris
B