Theory of nuclear spin dephasing and relaxation by optically illuminated nitrogen-vancy center

TL;DR

This paper develops an analytical and numerical framework to understand nuclear spin dephasing and relaxation caused by optical illumination of NV centers, revealing control mechanisms and explaining puzzling experimental observations.

Contribution

It provides a new analytical formula for nuclear spin dissipation during optical processes, linking it to external magnetic fields and electron hopping effects, advancing understanding of NV center spin dynamics.

Findings

Analytical formula matches experimental data reasonably well.

Nuclear spin dissipation can be controlled by magnetic field tuning.

Electron hopping significantly contributes to nuclear spin dephasing even under saturated optical pumping.

Abstract

Dephasing and relaxation of the nuclear spins coupled to the nitrogen-vacancy (NV) center during optical initialization and readout is an important issue for various applications of this hybrid quantum register. Here we present both an analytical description and a numerical simulation for this process, which agree reasonably with the experimental measurements. For the NV center under cyclic optical transition, our analytical formula not only provide a clear physics picture, but also allows controlling the nuclear spin dissipation by tuning an external magnetic field. For more general optical pumping, our analytical formula reveals significant contribution to the nuclear spin dissipation due to electron random hopping into/out of the $m=0$ (or $m=\pm1$) subspace. This contribution is not suppressed even under saturated optical pumping and/or vanishing magnetic field, thus providing a possible solution to the puzzling observation of nuclear spin dephasing in zero perpendicular magnetic field [M. V. G. Dutt \textit{et al}., Science \textbf{316}, 1312 (2007)]. It also implies that enhancing the degree of spin polarization of the nitrogen-vacancy center can reduce the effect of optical induced nuclear spin dissipation.