π phases in balanced fermionic superfluids on spin-dependent optical lattices.

Pi Phases in Balanced Fermionic Superfluids on Spin-Dependent Optical Lattices

Spin-Orbit Driven Transitions Between Mott Insulators and Finite Momentum Superfluids of Bosons in Optical Lattices

Synthetic spin-orbit coupling in ultracold atomic gases can be taken to extremes rarely found in solids. We study a two dimensional Hubbard model of bosons in an optical lattice in the presence of spin-orbit coupling strong enough to drive direct transitions from Mott insulators to superfluids. Here we find phase-modulated superfluids with finite momentum that are generated entirely by spin-orb...

Two-component Fermi gas on internal-state-dependent optical lattices.

We study the phase diagram of a one-dimensional, two-component (i.e., pseudo-"spin"-(1/2)) ultracold atomic Fermi gas. The two atom species can have different hopping or mass. A very rich phase diagram for equal densities of the species is found, containing Mott insulators and superfluids. We also discuss coupling such 1D systems and the experimental signatures of the phases. In particular, we ...

Fractional excitation in one-dimensional two species fermionic superfluids

We study one-dimensional two-species fermionic superfluids with order parameter twisted by an angle φ at the two ends. By solving the corresponding Bogoliubov-de-Gennes equation, we obtain the U(1) soliton state which turns out to carry φS/(2π) spin, where S is the spin of single fermion. For Z2 soliton with φ = π, the localized state carries only 1/2 of a single fermion spin. To conserve the t...

Competing superfluid orders in spin-orbit-coupled fermionic cold-atom optical lattices

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, a superconducting state with nonzero total momentum Cooper pairs in a large magnetic field, was first predicted about 50 years ago and has since become an important concept in many branches of physics. Despite an intensive search in various materials, unambiguous experimental evidence for the FFLO phase is still lacking in experiments. In this ...