Liquid crystal phases of two-dimensional dipolar gases and Berezinskii-Kosterlitz-Thouless melting

TL;DR

This paper investigates the quantum liquid crystal phases in a two-dimensional dipolar gas, analyzing phase stability, topological defect-driven melting, and critical temperatures, with implications for experimental realization of quantum liquid and superfluid phases.

Contribution

It provides a detailed quantum phase diagram of a 2D dipolar gas, including calculations of stiffness constants and microscopic analysis of stripe melting, advancing understanding of quantum liquid crystals.

Findings

Identification of stripe, nematic, and supersolid phases

Calculation of critical temperatures for phase transitions

Microscopic analysis of topological defect-driven melting

Abstract

Liquid crystals are phases of matter intermediate between crystals and liquids. Whereas classical liquid crystals have been known for a long time and are used in electro-optical displays, much less is known about their quantum counterparts. There is growing evidence that quantum liquid crystals play a central role in many electron systems including high temperature superconductors, but a quantitative understanding is lacking due to disorder and other complications. Here, we analyse the quantum phase diagram of a two-dimensional dipolar gas, which exhibits stripe, nematic and supersolid phases. We calculate the stiffness constants determining the stability of the nematic and stripe phases, and the melting of the stripes set by the proliferation of topological defects is analysed microscopically. Our results for the critical temperatures of these phases demonstrate that a controlled study of the interplay between quantum liquid and superfluid phases is within experimental reach for the first time, using dipolar gases.