The phase-separation mechanism of a binary mixture in a ring trimer

TL;DR

This paper investigates the phase separation mechanisms in a binary mixture within a ring trimer, revealing how interaction ratios influence ground states, quantum state structures, and entanglement properties, with implications for complex lattice systems.

Contribution

It introduces a detailed analysis of phase transitions and entanglement features in a three-well system, highlighting the double mixing-demixing transition and its quantum signatures.

Findings

Identification of three distinct ground-state configurations.

Observation of singularities in Entanglement Entropy at critical points.

Confirmation of a two-step phase separation process.

Abstract

We show that, depending on the ratio between the inter- and the intra-species interactions, a binary mixture trapped in a three-well potential with periodic boundary conditions exhibits three macroscopic ground-state configurations which differ in the degree of mixing. Accordingly, the corresponding quantum states feature either delocalization or a Schr\"odinger cat-like structure. The two-step phase separation occurring in the system, which is smoothed by the activation of tunnelling processes, is confirmed by the analysis of the energy spectrum that collapses and rearranges at the two critical points. In such points, we show that also Entanglement Entropy, a quantity borrowed from quantum-information theory, features singularities, thus demonstrating its ability to witness the double mixining-demixing phase transition. The developed analysis, which is of interest to both the experimental and theoretical communities, opens the door to the study of the demixing mechanism in complex lattice geometries.