Cavity Quantum Electrodynamics Effects with Nitrogen Vacancy Center Spins in Diamond and Microwave Resonators at Room Temperature

TL;DR

This paper investigates the potential for observing cavity quantum electrodynamics effects at room temperature using ensembles of nitrogen vacancy center spins in diamond, highlighting the role of optical spin-cooling in overcoming thermal excitation challenges.

Contribution

It demonstrates through simulations that optical spin-cooling can enable strong collective coupling and C-QED effects at room temperature with NV center ensembles.

Findings

Thermal excitation reduces collective coupling at room temperature.

Optical spin-cooling can restore high-symmetry Dicke states.

Room-temperature C-QED effects are feasible with current resonators.

Abstract

Cavity quantum electrodynamics (C-QED) effects, such as Rabi splitting, Rabi oscillations and superradiance, have been demonstrated with nitrogen vacancy center spins in diamond in microwave resonators at cryogenic temperature. In this article we explore the possibility to realize strong collective coupling and the resulting C-QED effects with ensembles of spins at room temperature. Thermal excitation of the individual spins by the hot environment leads to population of collective Dicke states with low symmetry and a reduced collective spin-microwave field coupling. However, we show with simulations that the thermal excitation can be compensated by spin-cooling via optical pumping. The resulting population of Dicke states with higher symmetry implies strong coupling with currently available high-quality resonators and enables C-QED effects at room temperature with potential applications in quantum sensing and quantum information processing.