The nitrogen-vacancy center in diamond, owing to its optically addressable and long-lived electronic spin, is an attractive resource for the generation of remote entangled states. However, the center's low native fraction of coherent photon emission, ∼3\%, strongly reduces the achievable spin-photon entanglement rates. Here, we couple a nitrogen-vacancy center with a narrow extrinsically broadened linewidth (\unit[159]{MHz}), hosted in a micron-thin membrane, to the mode of an open optical microcavity. The resulting Purcell factor of ∼1.8 increases the fraction of zero-phonon line photons to above 44\%, leading to coherent photon emission rates exceeding four times the state of the art under non-resonant excitation. Bolstered by the enhancement provided by the cavity, we for the first time measure resonance fluorescence without any temporal filtering with >10 signal-to-laser background ratio. Our microcavity platform would increase spin-spin entanglement success probabilities by more than an order of magnitude compared to existing implementations. Selective enhancement of the center's zero-phonon transitions could furthermore unlock efficient application of quantum optics techniques such as wave-packet shaping or all-optical spin manipulation.
@article{arxiv.2403.04611,
title = {Cavity-assisted resonance fluorescence from a nitrogen-vacancy center in diamond},
author = {Viktoria Yurgens and Yannik Fontana and Andrea Corazza and Brendan J. Shields and Patrick Maletinsky and Richard J. Warburton},
journal= {arXiv preprint arXiv:2403.04611},
year = {2024}
}