# Cooperative Light Emission in the Presence of Strong Inhomogeneous Broadening

## TL;DR

This paper investigates how an ensemble of two-level systems with inhomogeneous broadening exhibits a phase transition in photon emission when coupled to a cavity with a linearly changing frequency, revealing critical dynamics and potential experimental observation.

## Contribution

It demonstrates the existence of a sharp phase transition in cooperative emission under strong inhomogeneous broadening with a linearly swept cavity frequency, including the scaling behavior and experimental feasibility.

## Key findings

- A phase transition occurs near a critical sweep rate.
- The scaling exponent of the transition is determined.
- Potential observation in NV centers in diamond is proposed.

## Abstract

We study photon emission by an ensemble of two-level systems, with strong inhomogeneous broadening and coupled to a cavity mode whose frequency has linear time-dependence. The analysis shows that, regardless the distribution of energy level splittings, a sharp phase transition occurs between the weak and strong cooperative emission phases near a critical photonic frequency sweeping rate. The associated scaling exponent is determined. We suggest that this phase transition can be observed in an ensemble of negatively charged NV centers in diamond interacting with a microwave half-wavelength cavity mode even in the regime of weak coupling and at strong disorder of two-level splittings.