Enhanced Spectral Density of a Single Germanium Vacancy Center in a Nanodiamond by Cavity-Integration

TL;DR

This paper demonstrates coupling a single germanium vacancy center in a nanodiamond to a high-finesse Fabry-Pérot microcavity, significantly enhancing its spectral density and paving the way for quantum network applications.

Contribution

It introduces a method to transfer and couple a GeV- center in a nanodiamond to an open microcavity with high finesse under ambient conditions, enabling improved quantum optics experiments.

Findings

48-fold spectral density enhancement observed

Coupling achieved with high-finesse cavity (F=7700)

Potential for cryogenic spin-photon applications

Abstract

Color centers in diamond, among them the negatively-charged germanium vacancy (GeV$^-$), are promising candidates for many applications of quantum optics such as a quantum network. For efficient implementation, the optical transitions need to be coupled to a single optical mode. Here, we demonstrate the transfer of a nanodiamond containing a single ingrown GeV- center with excellent optical properties to an open Fabry-P\'erot microcavity by nanomanipulation utilizing an atomic force microscope. Coupling of the GeV- defect to the cavity mode is achieved, while the optical resonator maintains a high finesse of F = 7,700 and a 48-fold spectral density enhancement is observed. This article demonstrates the integration of a GeV- defect with a Fabry-P\'erot microcavity under ambient conditions with the potential to extend the experiments to cryogenic temperatures towards an efficient spin-photon platform.