Interaction-induced chiral-transport inversion

TL;DR

This paper reveals how isotropic interactions in a bosonic flux ladder can reverse chiral transport through interaction-driven band inversion and bound-state formation, challenging conventional assumptions about isotropic interactions.

Contribution

It uncovers the dual mechanisms of occupation inversion and bound-state formation causing chiral transport reversal in interacting bosonic systems.

Findings

Interaction-driven band-occupation inversion causes chiral transport reversal.

Two-body bound states with reversed chirality dominate few-body dynamics.

Isotropic interactions can bias density transport contrary to traditional beliefs.

Abstract

We investigate the chiral dynamics of locally interacting bosons in a two-leg flux ladder, where on-site interactions, despite being fully isotropic, counterintuitively reverse the flux-induced chiral transport of density distribution. For a Bose-Einstein condensate (in the mean-field regime), this reversal arises from an interactiondriven dynamical band-occupation inversion, which selectively populates single-particle states of the opposing chirality. Strikingly, the chiral-transport inversion has a few-body, hence beyond-mean-field, origin, as the formation of two-body bound states with reversed chirality dominates the few-body dynamics. This dual pathway, that is, occupation inversion and bound-state formation, underlies the chiral-transport inversion, which challenges the conventional wisdom that isotropic interactions cannot bias density transport. Our work reveals the interplay between interactions and chirality and highlights how correlations engineer exotic quantum transport.