title: BCS-BEC crossover and topological phase transition in 3D spin-orbit coupled degenerate Fermi gases.
abstract: We investigate the BCS-BEC crossover in three-dimensional degenerate Fermi gases in the presence of spin-orbit coupling (SOC) and Zeeman field. We show that the superfluid order parameter destroyed by a large Zeeman field can be restored by the SOC. With increasing strengths of the Zeeman field, there is a series of topological quantum phase transitions from a nontopological superfluid state with fully gapped fermionic spectrum to a topological superfluid state with four topologically protected Fermi points (i.e., nodes in the quasiparticle excitation gap) and then to a second topological superfluid state with only two Fermi points. The quasiparticle excitations near the Fermi points realize the long-sought low-temperature analog of Weyl fermions of particle physics. We show that the topological phase transitions can be probed using the experimentally realized momentum-resolved photoemission spectroscopy.
authors.affiliation: Department of Physics and Astronomy, Washington State University, Pullman, Washington, 99164, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.forename: Sumanta
authors.initials: S
authors.lastname: Tewari
authors.forename: Chuanwei
authors.initials: C
authors.lastname: Zhang