Dipolar Gases in Coupled One-Dimensional Lattices

TL;DR

This paper explores the behavior of dipolar bosons in coupled one-dimensional lattices, revealing how interactions lead to ordered phases, soliton pairing, and competition between crystalline and liquid states.

Contribution

It introduces the phenomenon of soliton pairing in coupled 1D dipolar systems and analyzes the effects of hopping and interactions on phase competition.

Findings

Complete devil's staircase of ordered phases at zero hopping.

Solitons from different tubes can bind into pairs for certain fillings.

Competition between Mott crystalline phases and liquid of defects.

Abstract

We consider dipolar bosons in two tubes of one-dimensional lattices, where the dipoles are aligned to be maximally repulsive and the particle filling fraction is the same in each tube. In the classical limit of zero inter-site hopping, the particles arrange themselves into an ordered crystal for any rational filling fraction, forming a complete devil's staircase like in the single tube case. Turning on hopping within each tube then gives rise to a competition between the crystalline Mott phases and a liquid of defects or solitons. However, for the two-tube case, we find that solitons from different tubes can bind into pairs for certain topologies of the filling fraction. This provides an intriguing example of pairing that is purely driven by correlations close to a Mott insulator.