Efficient Photon Coupling from a Diamond Nitrogen Vacancy Centre by Integration with Silica Fibre

TL;DR

This paper presents a compact, efficient method for coupling photons from diamond NV centers to optical fibres, achieving high collection efficiency and enabling robust quantum networking interfaces.

Contribution

The authors demonstrate a novel integrated system combining tapered diamond waveguides with silica fibres for efficient photon transfer from NV centers.

Findings

Collection efficiency of 18-40% achieved.

Single photon count rate exceeds 700 kHz.

Near-unity efficiency predicted by numerical optimization.

Abstract

A central goal in quantum information science is to efficiently interface photons with single optical modes for quantum networking and distributed quantum computing. Here, we introduce and experimentally demonstrate a compact and efficient method for the low-loss coupling of a solid-state qubit, the nitrogen vacancy (NV) centre in diamond, with a single-mode optical fibre. In this approach, single-mode tapered diamond waveguides containing exactly one high quality NV memory are selected and integrated on tapered silica fibres. Numerical optimization of an adiabatic coupler indicates that near-unity-efficiency photon transfer is possible between the two modes. Experimentally, we find an overall collection efficiency between 18-40 % and observe a raw single photon count rate above 700 kHz. This integrated system enables robust, alignment-free, and efficient interfacing of single-mode optical fibres with single photon emitters and quantum memories in solids.