Chiral Quantum Phases and Tricriticality in a Dicke Triangle

TL;DR

This paper explores quantum tricriticality and exotic phases in a Dicke triangle system, revealing chiral superradiant phases, tricritical points, and their critical behavior, with potential implementations in optical and circuit QED systems.

Contribution

It introduces a novel Dicke triangle model exhibiting chiral superradiant phases and tricritical points, analyzing their critical properties and universality classes.

Findings

Identification of chiral superradiant phase with nonzero photon current

Discovery of chiral tricritical points with unique critical exponents

Potential for experimental realization in optical and circuit QED systems

Abstract

The existence of quantum tricriticality and exotic phases are found in a Dicke triangle (TDT) where three cavities, each one containing an ensemble of three-level atoms, are connected to each other through the action of an artificial magnetic field. The conventional superradiant phase (SR) is connected to the normal phase through first- and second-order boundaries, with tricritical points located at the intersection of such boundaries. Apart from the SR phase, a chiral superradiant (CSR) phase is found by tuning the artificial magnetic field. This phase is characterized by a nonzero photon current and its boundary presents chiral tricritical points (CTCPs). Through the study of different critical exponents, we are able to differentiate the universality class of the CTCP and TCP from that of second-order critical points, as well as find distinctive critical behavior among the two different superradiant phases. The TDT can be implemented in various systems, including atoms in optical cavities as well as the circuit QED system, allowing the exploration of a great variety of critical manifolds.