Strongly fluctuating fermionic superfluid in the attractive pi-flux Hubbard model

作者:Wu, Ya-Jie*; Zhou, Jiang; Kou, Su-Peng
来源:Physical Review A, 2014, 89(1): 013619.
DOI:10.1103/PhysRevA.89.013619

摘要

Ultracold atoms in an optical lattice provide a platform for realization of the superfluid (SF) state, a quantum order with paired charge-neutral fermions. In this paper, we study the SF state in the two-dimensional attractive Hubbard model with pi flux on each plaquette. The SF state in the pi-flux lattice model suffers very strong quantum fluctuations and the ground state becomes a possible quantum phase liquid state. In this phase, there exists Cooper pairing together with a finite energy gap for the atoms, but no long-range SF phase coherence exists at zero temperature. In addition, we discuss the properties of the SF vortices.