Bose-Hubbard triangular ladder in an artificial gauge field

TL;DR

This paper explores the complex phase diagram of interacting bosons on a triangular ladder with an artificial gauge field, revealing multiple chiral phases, phase transitions, and symmetry-breaking states through numerical and analytical methods.

Contribution

It introduces a detailed analysis of the phase diagram of bosons on a triangular ladder with gauge fields, highlighting new chiral and symmetry-breaking phases not previously characterized.

Findings

Identification of multiple chiral quantum phases.

Observation of superfluid to Mott-insulator transitions with Meissner or vortex character.

Discovery of a biased chiral superfluid state near flux π.

Abstract

We consider interacting bosonic particles on a two-leg triangular ladder in the presence of an artificial gauge field. We employ density matrix renormalization group numerical simulations and analytical bosonization calculations to study the rich phase diagram of this system. We show that the interplay between the frustration induced by the triangular lattice geometry and the interactions gives rise to multiple chiral quantum phases. Phase transition between superfluid to Mott-insulating states occur, which can have Meissner or vortex character. Furthermore, a state that explicitly breaks the symmetry between the two legs of the ladder, the biased chiral superfluid, is found for values of the flux close to $\pi$. In the regime of hardcore bosons, we show that the extension of the bond order insulator beyond the case of the fully frustrated ladder exhibits Meissner-type chiral currents. We discuss the consequences of our findings for experiments in cold atomic systems.