arXiv:1501.04785 · Physical Review A
Quantum phase transition of bosons in a shaken optical lattice
Jiao Miao, Boyang Liu, Wei Zheng
Abstract
Recently, the lattice shaking technique has been used to couple different Bloch bands resonantly. For the one-dimensional (1D) case in which shaking is along only one direction, experimental observation of domain-wall formation has been explained by superfluid Ising transition. Inspired by these, we generalize to a two-dimensional case in which shaking is along two orthogonal directions. Analogous to the 1D case, we find three different phases, the normal superfluid (NSF) phase, the ${D}_{4}$ symmetry-breaking superfluid $({D}_{4}\mathrm{SF})$ phase, and the Mott insulator (MI) phase. Furthermore, we demonstrate that an interaction effect induced by inhomogeneous band mixing can modify the critical shaking amplitude. Unlike in the 1D case, shaking types also can modify the critical shaking amplitude. We also construct a low-energy effective field theory to study the quantum criticality of bosons near the tricritical point of NSF, ${D}_{4}\mathrm{SF}$, and MI phases. Moreover, we find a Bose liquid with anisotropically algebraic order and propose to change a Bose-Einstein condensate into a noncondensed Bose liquid by tuning the shaking amplitude approaching the critical value.