Topological Superfluid and Majorana Zero Modes in Synthetic Dimension

TL;DR

This paper explores how attractive interactions induce topological superfluidity and Majorana zero modes in a synthetic dimension system modeled as a 2D lattice with chiral edge states, revealing robustness linked to symmetry.

Contribution

It demonstrates the emergence of topological superfluidity and Majorana modes in synthetic dimension systems with long-range Hubbard interactions, highlighting the role of symmetry and Chern number parity.

Findings

Attractive Hubbard interactions induce Cooper pairing between edge states.

The topological class depends on the parity of the Chern number.

Multiple zero modes are robust due to chiral symmetry.

Abstract

Recently it has been shown that multicomponent spin-orbit-coupled fermions in one-dimensional optical lattices can be viewed as spinless fermions moving in two-dimensional synthetic lattices with synthetic magnetic flux. The quantum Hall edge states in these systems have been observed in recent experiments. In this paper we study the effect of an attractive Hubbard interaction. Since the Hubbard interaction is long-range in the synthetic dimension, it is able to efficiently induce Cooper pairing between the counterpropagating chiral edge states. The topological class of the resultant one-dimensional superfluid is determined by the parity (even/odd) of the Chern number in the two-dimensional synthetic lattice. We also show the presence of a chiral symmetry in our model, which implies ${\rm Z}$ classification and the robustness of multiple zero modes when this symmetry is unbroken.