High-quality diamond confined open microcavity for diamond-based photonics

The nitrogen vacancy centre (NV) in diamond constitutes a promising node in a quantum network owing to its highly coherent, optically addressable electron spin. However, scalability to more than a few network nodes hinges on modest entanglement rates owing to poor extraction efficiency of coherent photons out of the host material. However, coupling single NV centres to a resonant microcavity can greatly enhance the photon flux, owing to the Purcell effect [1].

In this work we present an open Fabry-Perot microcavity containing a high-quality single crystalline diamond membrane [1,2]. We operate in a so-called “diamond confined” geometry, where the vacuum electric field is strongly confined to the diamond. We obtain Q-factors exceeding 100.000 and a finesse of 11.500 despite the fact that the vacuum field has an anti-node at the diamond-air interface. We develop a model to describe the losses associated with the diamond membrane. Hence, operating in the diamond-confined geometry is a potential route to a strong light-matter coupling. With the current design, Purcell factors exceeding 150 are predicted.

1 Phys. Rev. X 7, 031040 (2017)
2 Phys. Rev. Appl. 13, 014036 (2020)