Exploring helical phases of matter in bosonic ladders

TL;DR

This paper investigates strongly correlated helical phases in bosonic ladder models, identifying conditions for their experimental realization and characterizing their signatures through advanced theoretical methods.

Contribution

It identifies two helical phases in bosonic ladders at filling factor 1, with one accessible via simple on-site interactions suitable for optical lattice experiments.

Findings

Two strongly correlated helical phases identified at filling factor 1.

One phase can be realized with two-species hardcore bosons and on-site repulsions.

Signatures of the phases are sizable and stable across realistic parameters.

Abstract

Ladder models of ultracold atoms offer a versatile platform for the experimental and theoretical study of different phenomena and phases of matter linked to the interplay between artificial gauge fields and interactions. Strongly correlated helical states are known to appear for specific ratios of the particle and magnetic flux densities and they can often be interpreted as a one-dimensional limit of fractional quantum Hall states, thus being called pretopological. Their signatures, however, are typically hard to observe due to the small gaps characterizing these states. Here we investigate bosonic ladder models at filling factor 1. Based on bosonization, renormalization group and matrix product state simulations we pinpoint two strongly correlated helical phases appearing at this resonance. We show that one of them can be accessed in systems with two-species hardcore bosons and on-site repulsions only, thus amenable for optical lattice experiments. Its signatures are sizable and stable over a broad range of parameters for realistic system sizes.