Dissipative quantum phase transitions in electrically driven lasers

TL;DR

This paper predicts new quantum phase transitions in electrically driven laser systems with quantum dot circuits in microwave cavities, revealing controllable transitions between thermal, superbunched, and coherent photon emission states.

Contribution

It introduces the concept of quantum phase transitions in electrically driven lasing regimes without requiring deep strong light-matter couplings, expanding understanding of quantum optics in circuit QED.

Findings

Continuous phase transition from thermal to coherent photon emission.

Discontinuous transition from superbunched to coherent states in two-photon processes.

Electric field control of phase transition order and critical coupling.

Abstract

Embedding quantum dot circuits into microwave cavities has emerged as a novel platform for controlling photon emission statistics by electrical means. With such a circuit version of the Rabi model, we reveal previously undefined quantum phase transitions in electrically driven lasing regimes, which do not require deep strong light-matter couplings. For one-photon interaction, the scaling analysis indicates that the system undergoes a continuous phase transition from thermal to coherent photon emissions. Going beyond this, a discontinuous quantum phase transition from superbunched to coherent states in two-photon processes, accompanied by the bistability within a mean-field theory, is predicted. Both the order of phase transitions and the critical electron-photon coupling can be easily controlled by an electric field, while the tunneling current can be used as a fingerprint of such transitions. Our prediction, along with its extension to multiphoton processes, represents a key step towards accessing lasing phase transitions.