Chiral cavity-induced quantum phase transitions in a quantum ring

TL;DR

This paper investigates how a quantum ring in a gyrotropic cavity undergoes quantum phase transitions driven by ultrastrong light-matter coupling, leading to observable changes in angular momentum and emitted radiation.

Contribution

It demonstrates the occurrence of quantum phase transitions in a quantum ring without magnetic flux, induced by chiral cavity interactions in the ultrastrong coupling regime.

Findings

Discontinuous change in ground state current with light-matter coupling.

Angular momentum change detectable via emitted radiation.

Quantum phase transition analogous to Aharonov-Bohm effect.

Abstract

We consider a quantum ring placed in a gyrotropic cavity characterized by the energy splitting between the left and right circularly polarized modes. We show that despite the absence of constant magnetic field penetrating through the ring, in the regime of the ultrastrong light matter coupling, the total current in the ground state changes discontinuously with the light matter coupling in the direct analogy with the Aharonov-Bohm ring. We consider the driven-dissipative of the system and show that the discontinuous change of the total angular momentum can be directly probed via the spectral and statical properties of the radiation emitted by the system under weak coherent drive.