Quantum liquid-crystal order in resonant atomic gases

TL;DR

This paper reviews theoretical predictions of quantum liquid-crystalline phases in resonant atomic gases, highlighting novel ordered states like smectic and nematic phases arising from quantum fluctuations and interactions.

Contribution

It introduces the concept of quantum liquid-crystalline order in atomic gases, analyzing phase diagrams, transitions, and low-energy properties of these exotic states.

Findings

Prediction of smectic, nematic, and other liquid-crystalline phases in atomic gases.

Identification of phase transitions and fractional topological defects.

Analysis of low-energy excitations and fluctuation effects in these phases.

Abstract

I review recent studies that predict quantum liquid-crystalline orders in resonant atomic gases. As examples of such putative systems I will discuss an s-wave resonant imbalanced Fermi gas and a p-wave resonant Bose gas. In the former, the liquid-crystalline smectic, nematic and rich variety of other descendant states emerge from strongly quantum- and thermally- fluctuating Fulde-Ferrell and Larkin-Ovchinnikov states, driven by a competition between resonant pairing and Fermi-surface mismatch. In the latter, at intermediate detuning the p-wave resonant interaction generically drives Bose-condensation at a finite momentum, set by a competition between atomic kinetic energy and atom-molecule hybridization. Because of the underlying rotationally-invariant environment of the atomic gas trapped isotropically, the putative striped superfluid is a realization of a quantum superfluid smectic, that can melt into a variety of interesting phases, such as a quantum nematic. I will discuss the corresponding rich phase diagrams and transitions, as well the low-energy properties of the phases and fractional topological defects generic to striped superfluids and their fluctuation-driven descendants.