Spontaneous increase of magnetic flux and chiral-current reversal in bosonic ladders: Swimming against the tide

TL;DR

This paper investigates how interactions and symmetry breaking in bosonic ladder systems under magnetic flux lead to spontaneous flux increases and current reversals, revealing complex quantum behaviors observable in experiments.

Contribution

It uncovers the mechanism behind spontaneous flux increase and chiral-current reversal due to vortex lattice formation and symmetry breaking in bosonic ladders.

Findings

Interactions stabilize vortex lattices.

Vortex lattices cause current reversal.

Predictions applicable to quantum gas experiments.

Abstract

The interplay between spontaneous symmetry breaking in many-body systems, the wavelike nature of quantum particles and lattice effects produces an extraordinary behavior of the chiral current of bosonic particles in the presence of a uniform magnetic flux defined on a two-leg ladder. While non-interacting as well as strongly interacting particles, stirred by the magnetic field, circulate along the system's boundary in the counterclockwise direction in the ground state, interactions stabilize vortex lattices. These states break translational symmetry, which can lead to a reversal of the circulation direction. Our predictions could readily be accessed in quantum gas experiments with existing setups or in arrays of Josephson junctions.