Quantum Criticality of Liquid-Gas Transition in a Binary Bose Mixture

TL;DR

This paper investigates the quantum critical points in a binary Bose mixture undergoing a liquid-gas transition, revealing rich critical behaviors and providing insights into quantum liquid-gas criticality in ultracold atomic systems.

Contribution

It identifies and characterizes two distinct quantum critical points in a binary Bose mixture, advancing understanding of quantum liquid-gas phase transitions.

Findings

Existence of two critical points terminating the liquid-gas coexistence

Divergent susceptibility and phonon-mode softening near critical points

Enhanced density correlations at criticality

Abstract

Quantum liquid, in the form of a self-bound droplet, is stabilized by a subtle balance between the mean-field contribution and quantum fluctuations. While a liquid-gas transition is expected when such a balance is broken, it remains elusive whether liquid-gas critical points exist in the quantum regime. Here we study the quantum criticality in a binary Bose mixture undergoing the liquid-gas transition. We show that, beyond a narrow stability window of the self-bound liquid, a liquid-gas coexistence persists, which eventually transits into a homogeneous mixture. Importantly, we identify two distinct critical points where the liquid-gas coexistence terminates. These critical points are characterized by rich critical behaviors in their vicinity, including divergent susceptibility, unique phonon-mode softening, and enhanced density correlations. The liquid-gas transition and the critical points can be readily explored in ultracold atoms confined to a box potential. Our work highlights the thermodynamic approach as a powerful tool in revealing the quantum liquid-gas criticality, and paves the way for further studies of critical phenomena in quantum liquids.