Cavity Enhanced Spin Measurement of an NV Centre in Diamond

TL;DR

This paper introduces a cavity quantum electrodynamics-based method for high-efficiency, high-fidelity measurement of a single NV center's ground state spin in diamond, using low-intensity light to reduce non-spin-preserving transitions.

Contribution

It proposes a novel measurement scheme in the one-dimensional atom regime that does not require high Q cavities, simplifying experimental implementation.

Findings

Achieves a spin readout error rate of approximately 0.55%

Uses low-intensity laser probing to minimize non-spin-preserving transitions

Demonstrates a change in reflected light intensity enables effective spin state discrimination

Abstract

We propose a high efficiency high fidelity measurement of the ground state spin of a single NV center in diamond, using the effects of cavity quantum electrodynamics. The scheme we propose is based in the one dimensional atom or Purcell regime, removing the need for high Q cavities that are challenging to fabricate. The ground state of the NV center consists of three spin levels $^{3}A_{(m=0)}$ and $^{3}A_{(m=\pm1)}$ (the $\pm1$ states are near degenerate in zero field). These two states can undergo transitions to the excited ($^{3}E$) state, with an energy difference of $\approx7-10$ $\mu$eV between the two. By choosing the correct Q factor, this small detuning between the two transitions results in a dramatic change in the intensity of reflected light. We show the change in reflected intensity can allow us to read out the ground state spin using a low intensity laser with an error rate of $\approx5.5\times10^{-3}$, when realistic cavity and experimental parameters are considered. Since very low levels of light are used to probe the state of the spin we limit the number of florescence cycles, thereby limiting the non spin preserving transitions through the intermediate singlet state $^{1}A$.