We propose an efficient scheme for a coherent quantum interface between microwave and optical photons using nitrogen-vacancy (NV) centers in diamond. In this setup, an NV center ensemble is simultaneously coupled to an optical and a microwave cavity. We show that, by using the collective spin excitation modes as an intermediary, quantum states can be transferred between the microwave cavity and the optical cavity through either a double-swap scheme or a dark-state protocol. This hybrid quantum interface may provide interesting applications in single microwave photon detections or quantum information processing.
@article{arxiv.1709.04852,
title = {Quantum microwave-optical interface with nitrogen-vacancy centers in diamond},
author = {Bo Li and Peng-Bo Li and Yuan Zhou and Sheng-Li Ma and Fu-Li Li},
journal= {arXiv preprint arXiv:1709.04852},
year = {2017}
}