Theory of the optical spinpolarization loop of the nitrogen-vacancy center in diamond

TL;DR

This paper develops a comprehensive theoretical model of the optical spinpolarization process in the NV center in diamond, explaining spectral asymmetries and calculating transition rates with good experimental agreement.

Contribution

It introduces a detailed theory incorporating electron-phonon couplings, Jahn-Teller effects, and spin-orbit interactions to understand the intersystem crossing in NV centers.

Findings

Good agreement with experimental spectra and transition rates

Explanation of spectral asymmetry between emission and absorption

A theoretical framework applicable to other solid-state qubits

Abstract

The nitrogen-vacancy (NV) center in diamond is of high importance in quantum information processing applications which relies on the efficient optical polarization of its electron spin. However, the full optical spinpolarization process, in particular, the intersystem crossing between the shelving singlet state and the ground state triplet, is not understood. Here we develop a detailed theory on this process which involves strong electron-phonon couplings and correlation of electronic states that can be described as a combination of pseudo and dynamic Jahn-Teller interactions together with spin-orbit interaction. Our theory provides an explanation for the asymmetry between the observed emission and absorption spectra of the singlet states. We apply density functional theory to calculate the intersystem crossing rates and the optical spectra of the singlets and we obtain good agreement with the experimental data. As NV center serves as a template for other solid-state-defect quantum bit systems, our theory provides a toolkit to study them that might help optimize their quantum bit operation.