\pi-flux Dirac bosons and topological edge excitations in a bosonic chiral p-wave superfluid

TL;DR

This paper explores topological excitations in a bosonic chiral p-wave superfluid, revealing Dirac bosons with Berry flux and topologically protected edge modes, with potential experimental realization.

Contribution

It introduces a topological analysis of elementary excitations in a bosonic chiral p-wave superfluid, highlighting the emergence of Dirac bosons and edge states upon population imbalance.

Findings

Elementary excitations exhibit Dirac bosons with π Berry flux.

Population imbalance induces a gap and nonzero Chern number.

Topologically protected edge modes can be realized experimentally.

Abstract

We study the topological properties of elementary excitations in a staggered $p_x \pm i p_y$ Bose-Einstein condensate realized in recent orbital optical lattice experiments. The condensate wave function may be viewed as a configuration space variant of the famous $p_x+ ip_y$ momentum space order parameter of strontium ruthenate superconductors. We show that its elementary excitation spectrum possesses Dirac bosons with $\pi$ Berry flux. Remarkably, if we induce a population imbalance between the $p_x+ip_y$ and $p_x-ip_y$ condensate components, a gap opens up in the excitation spectrum resulting in a nonzero Chern invariant and topologically protected edge excitation modes. We give a detailed description on how our proposal can be implemented with standard experimental technology.