Coherence of an optically illuminated single nuclear spin qubit

TL;DR

This paper studies how the coherence of a single nuclear spin qubit in diamond is maintained during optical interrogation of an adjacent electronic spin, revealing a motional averaging effect that preserves coherence.

Contribution

It introduces a spin-fluctuator model to describe nuclear spin dynamics under optical excitation and demonstrates a method to preserve nuclear spin coherence despite electronic transitions.

Findings

Nuclear spin coherence can be preserved after many optical cycles.

The spin-fluctuator model accurately describes the nuclear spin dynamics.

Potential for isolating nuclear spins from electronic environment.

Abstract

We investigate the coherence properties of individual nuclear spin quantum bits in diamond [Dutt et al., Science, 316, 1312 (2007)] when a proximal electronic spin associated with a nitrogen-vacancy (NV) center is being interrogated by optical radiation. The resulting nuclear spin dynamics are governed by time-dependent hyperfine interaction associated with rapid electronic transitions, which can be described by a spin-fluctuator model. We show that due to a process analogous to motional averaging in nuclear magnetic resonance, the nuclear spin coherence can be preserved after a large number of optical excitation cycles. Our theoretical analysis is in good agreement with experimental results. It indicates a novel approach that could potentially isolate the nuclear spin system completely from the electronic environment.