Purcell-Enhanced Single-Photon Emission from Nitrogen-Vacancy Centers Coupled to a Tunable Microcavity

Abstract

Optical microcavities are a powerful tool to enhance spontaneous emission of individual quantum emitters. However, the broad emission spectra encountered in the solid state at room temperature limit the influence of a cavity, and call for ultra-small mode volume. We demonstrate Purcellenhanced single photon emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to a tunable fiber-based microcavity with a mode volume down to 1.0 λ 3 . We record cavity-enhanced fluorescence images and study several single emitters with one cavity. The Purcell effect is evidenced by enhanced fluorescence collection, as well as tunable fluorescence lifetime modification, and we infer an effective Purcell factor of up to 2.0. With numerical simulations, we furthermore show that a novel regime for light confinement can be achieved, where a Fabry-Perot mode is combined with additional mode confinement by the nanocrystal itself. In this regime, effective Purcell factors of up to 11 for NV centers and 63 for silicon vacancy centers are feasible, holding promise for bright single photon sources and efficient spin readout under ambient conditions. II. ULTRA-SMALL MODE VOLUME TUNABLE CAVITYThe microcavity is assembled of a planar mirror onto which the sample is applied, and a concave mirror on the tip of an optical fiber [26], see Fig. 1(a). The tip of the cavity fiber is shaped by advanced CO 2 laser machining [34,35]. In a first step, the extent of the endfacet is tapered to enable sub-micron mirror separations, arXiv:1606.00167v2 [quant-ph]

Design and low-temperature characterization of a tunable microcavity for diamond-based quantum networks

“…[13][14][15][16] In recent years, the open Fabry-Perot microcavity 17 has emerged as a promising platform for diamond emitters. [18][19][20][21][22] Such a microcavity provides in-situ spatial and spectral tunability, while reaching strong field confinement due to its small mode volume V and high quality factor Q. Moreover, this architecture allows for the use of diamond slabs 23 in which the NV center can be relatively far removed from surfaces and thus exhibit bulklike optical properties, as required for quantum network applications.…”

Tunable Open‐Access Microcavities for Solid‐State Quantum Photonics and Polaritonics

“…The authors also carried out systematic studies using concave mirrors with a series of RoCs ranging from 4 to 25 µm, and concluded that RoC = 8 µm enabled the best device performance by the interplay between cavity feeding and photon extraction. With fiber‐based cavities, Kaupp et al., demonstrated Purcell enhancement up to two of NV centers in nanodiamonds in 2016 . In 2017, Riedel et al.…”

On-chip High-finesse Fabry-Perot Microcavities for Optical Sensing and Quantum Information

“…This modification was historically treated by Purcell using a semi-classical approach, with the essential results subsequently confirmed by rigorous quantum mechanical treatments [23]. For example, assuming an atom located at a field maximum (in an otherwise empty cavity, such that refractive index n =1) and with its electric dipole aligned to the cavity mode field, and also assuming the atomic transition is exactly matched to a cavity resonance and with γ < κ [53,71], then the enhancement of the radiative decay rate is given by the so-called Purcell factor:…”

“…In the case of solid-state emitters, which have relatively large g, this implies that small VM is particularly critical (i.e. since increased k implies reduced Q) [53,71]. …”