title: Ground states of a Bose-Einstein Condensate in a one-dimensional laser-assisted optical lattice.
abstract: We study the ground-state behavior of a Bose-Einstein Condensate (BEC) in a Raman-laser-assisted one-dimensional (1D) optical lattice potential forming a multilayer system. We find that, such system can be described by an effective model with spin-orbit coupling (SOC) of pseudospin (N-1)/2, where N is the number of layers. Due to the intricate interplay between atomic interactions, SOC and laser-assisted tunnelings, the ground-state phase diagrams generally consist of three phases-a stripe, a plane wave and a normal phase with zero-momentum, touching at a quantum tricritical point. More important, even though the single-particle states only minimize at zero-momentum for odd N, the many-body ground states may still develop finite momenta. The underlying mechanisms are elucidated. Our results provide an alternative way to realize an effective spin-orbit coupling of Bose gas with the Raman-laser-assisted optical lattice, and would also be beneficial to the studies on SOC effects in spinor Bose systems with large spin.
authors.affiliation: Department of Physics, Capital Normal University, Beijing, 100048, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Department of Physics, Capital Normal University, Beijing, 100048, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
authors.affiliation: College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wen
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: W-M
authors.initials: WM
authors.lastname: Liu
authors.affiliation: Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio Ave. 3, LT-10222 Vilnius, Lithuania.
authors.forename: G
authors.initials: G
authors.lastname: Juzeliūnas
authors.affiliation: Department of Physics, Capital Normal University, Beijing, 100048, China.
authors.forename: An-Chun
authors.initials: AC
authors.lastname: Ji