Floquet FFLO superfluids and Majorana fermions in a shaken fermionic optical lattice

TL;DR

This paper proposes a new method using shaken optical lattices to realize and observe FFLO superfluids and Majorana fermions in cold atom systems, providing a promising platform for topological quantum states.

Contribution

It demonstrates how to engineer FFLO superfluids and Majorana fermions in shaken optical lattices through tunable parameters and orbital couplings, a novel approach in cold atom research.

Findings

Shaken lattice parameters control pseudo-spin coupling.

FFLO superfluids and Majorana fermions can be realized in this system.

System transitions from topological insulator to superfluid phases.

Abstract

Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids, Cooper pairings with finite momentum, and Majorana fermions (MFs), quasiparticles with non-Abelian exchange statistics, are two topics under intensive investigation in the past several decades, but unambiguous experimental evidences for them have not been found yet in any physical system. Here we show that the recent experimentally realized cold atom shaken optical lattice provides a new pathway to realize FFLO superfluids and MFs. By tuning shaken lattice parameters (shaking frequency and amplitude), various coupling between the s- and p-orbitals of the lattice (denoted as the pseudo-spins) can be generated. We show that the combination of the inverted s- and p-band dispersions, the engineered pseudo-spin coupling, and the attractive on-site atom interaction, naturally allows the observation of FFLO superfluids as well as MFs in different parameter regions. While without interaction the system is a topological insulator (TI) with edge states, the MFs in the superfluid may be found to be in the conduction or valence band, distinguished from previous TI-based schemes that utilize edge states inside the band gap.