Orbital hybridized topological Fulde-Ferrel superfluidity in a noncentrosymmetric optical lattice

TL;DR

This paper demonstrates that noncentrosymmetric optical lattices can host topological superfluid states with Majorana fermions, achieved through orbital hybridization and attractive fermions, with observable signatures in cold gas experiments.

Contribution

It introduces a new mechanism for topological band structures via orbital hybridization in noncentrosymmetric lattices, leading to topological Fulde-Ferrell superfluidity with Majorana edge states.

Findings

Topological non-trivial Bloch bands arise in noncentrosymmetric lattices.

A topological Fulde-Ferrell superfluid state is predicted with finite momentum.

Majorana fermions are supported on the superfluid edges.

Abstract

Topological phases like topological insulators or superconductors are fascinating quantum states of matter, featuring novel properties such as emergent chiral edge states or Majorana fermions with non-Abelian braiding statistics. The recent experimental implementation of optical lattices with highly tunable geometry in cold gases opens up a new thrust on exploring these novel quantum states. Here we report that the topological non-trivial Bloch bands can arise naturally in a noncentrosymmetric lattice. It induces a controllable orbital hybridization, producing the topological band structure. In such bands, when considering attractive fermionic atoms, we find a topological Fulde-Ferrell superfluid state with finite center-of-mass momentum in the presence of onsite rotation. This topological superfluid supports Majorana fermions on its edges. Experimental signatures are predicted for cold gases in radio-frequency spectroscopy.