Intrinsic Anomalous Hall Effect in a Bosonic Chiral Superfluid

TL;DR

This paper predicts an intrinsic anomalous Hall effect in a bosonic chiral superfluid, specifically a p-band Bose-Einstein condensate in a 2D optical lattice, with detailed theoretical analysis and experimental implications.

Contribution

It introduces the first theoretical prediction of an intrinsic anomalous Hall effect in a bosonic superfluid, linking it to finite loop current correlations and band Berry curvature.

Findings

High frequency Hall conductivity linked to loop current correlations

DC Hall conductivity related to band Berry curvature

Experimental probes suggested for observing the effect

Abstract

The anomalous Hall effect has had a profound influence on the understanding of many electronic topological materials but is much less studied in their bosonic counterparts. We predict that an intrinsic anomalous Hall effect exists in a recently realized bosonic chiral superfluid, a $p$-band Bose-Einstein condensate in a 2D hexagonal boron nitride optical lattice [X. Wang et al., https://www.nature.com/articles/s41586-021-03702-0 Nature (London) 596, 227 (2021)]. We evaluate the frequency-dependent Hall conductivity within a multi-orbital Bose-Hubbard model that accurately captures the real experimental system. We find that in the high frequency limit, the Hall conductivity is determined by finite loop current correlations on the $s$-orbital residing sublattice, the latter a defining feature of the system's chirality. In the opposite limit, the dc Hall conductivity can trace its origin back to the non-interacting band Berry curvature at the condensation momentum, although the contribution from atomic interactions can be significant. We discuss available experimental probes to observe this intrinsic anomalous Hall effect at both zero and finite frequencies.