Quantum phase transitions of a two-leg bosonic ladder in an artificial gauge field

TL;DR

This paper explores quantum phase transitions in a two-leg bosonic ladder under an artificial gauge field, revealing how interleg interactions and flux influence various phases and transitions, including Meissner, vortex, and density wave phases.

Contribution

It introduces a detailed analysis of how interleg interactions and flux affect phase transitions and phase diagrams in bosonic ladders, highlighting differences between attractive and repulsive interactions.

Findings

Interleg interaction converts the transition from Meissner to Vortex phase into an Ising-type transition.

A disorder point causes correlation functions to develop damped sinusoid behavior, indicating vortex phase melting.

Repulsive interactions favor the Meissner phase at low flux and induce a second incommensuration phase at intermediate flux.

Abstract

We consider a two leg bosonic ladder in a $U(1)$ gauge field with both interleg hopping and interleg repulsion. As a function of the flux, the interleg interaction converts the commensurate-incommensurate transition from the Meissner to a Vortex phase, into an Ising-type of transition towards a density wave phase. A disorder point is also found after which the correlation functions develop a damped sinusoid behavior signaling a melting of the vortex phase. We discuss the differences on the phase diagram for attractive and repulsive interleg interaction. In particular, we show how repulsion favors the Meissner phase at low-flux and a phase with a second incommensuration in the correlation functions for intermediate flux, leading to a richer phase diagram than in the case of interleg attraction. The effect of the temperature on the chiral current is also discussed.