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.
Department of Engineering Science and Physics, The College of Staten Island, City University of New York, Staten Island, New York 10314, USA.
Anatoly
A
Kuklov
Nikolay
N
Prokof'ev
Boris
B
Svistunov