Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond

TL;DR

This paper demonstrates tunable cavity enhancement of the zero phonon line of a nitrogen-vacancy center in diamond, significantly increasing emission rates and paving the way for scalable quantum computing with solid-state spin qubits.

Contribution

It introduces a tunable open cavity system with in-situ resonance control that enhances NV center emission at cryogenic temperatures, advancing quantum photonics applications.

Findings

Signal from NV zero phonon line enhanced by ~10 times

Overall emission rate increased by 40%

Cavity resonance tuned in situ with piezoelectric actuators

Abstract

We demonstrate the tunable enhancement of the zero phonon line of a single nitrogen-vacancy color center in diamond at cryogenic temperature. An open cavity fabricated using focused ion beam milling provides mode volumes as small as 1.24 $\mu$m$^3$. In-situ tuning of the cavity resonance is achieved with piezoelectric actuators. At optimal coupling of the full open cavity the signal from individual zero phonon line transitions is enhanced by about a factor of 10 and the overall emission rate of the NV$^-$ center is increased by 40% compared with that measured from the same center in the absence of cavity field confinement. This result is important for the realization of efficient spin-photon interfaces and scalable quantum computing using optically addressable solid state spin qubits.