Design and low-temperature characterization of a tunable microcavity for   diamond-based quantum networks
  We report on the fabrication and characterization of a Fabry-Perot microcavity enclosing a thin diamond membrane at cryogenic temperatures. The cavity is designed to enhance resonant emission of single nitrogen-vacancy centers by allowing spectral and spatial tuning while preserving the optical properties observed in bulk diamond. We demonstrate cavity finesse at cryogenic temperatures within the range of F = 4,000-12,000 and find a sub-nanometer cavity stability. Modeling shows that coupling nitrogen-vacancy centers to these cavities could lead to an increase of remote entanglement success rates by three orders of magnitude. 
S. Bogdanovic, S.B. van Dam, C. Bonato, L.C. Coenen, A.J. Zwerver, B.   Hensen, M.S.Z. Liddy, T. Fink, A. Reiserer, M. Lonca...
quant-ph cond-mat.mes-hall