title: Unconventional pairings of spin-orbit coupled attractive degenerate Fermi gas in a one-dimensional optical lattice.
abstract: Understanding novel pairings in attractive degenerate Fermi gases is crucial for exploring rich superfluid physics. In this report, we reveal unconventional pairings induced by spin-orbit coupling (SOC) in a one-dimensional optical lattice, using a state-of-the-art density-matrix renormalization group method. When both bands are partially occupied, we find a strong competition between the interband Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and intraband Bardeen-Cooper-Schrieffer (BCS) pairings. In particular, for the weak and moderate SOC strengths, these two pairings can coexist, giving rise to a new phase called the FFLO-BCS phase, which exhibits a unique three-peak structure in pairing momentum distribution. For the strong SOC strength, the intraband BCS pairing always dominates in the whole parameter regime, including the half filling. We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field. Our results are qualitatively different from recent mean-field predictions. Finally, we address that our predictions could be observed in a weaker trapped potential.
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.
authors.forename: Junjun
authors.initials: J
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.
authors.forename: Xiaofan
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Physics and Center for Quantum Coherence, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Pak Hong
authors.initials: PH
authors.lastname: Chui
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.
authors.forename: Kuang
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Physics and Center for Quantum Coherence, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Shi-jian
authors.initials: SJ
authors.lastname: Gu
authors.affiliation: Department of Physics and Center for Quantum Coherence, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.
authors.forename: Suotang
authors.initials: S
authors.lastname: Jia