Temperature-dependent spin-lattice relaxation of the nitrogen-vacancy spin triplet in diamond

TL;DR

This study measures how temperature affects the spin-lattice relaxation of NV centers in diamond, combining experimental data with ab initio theory to understand phonon interactions across a wide temperature range.

Contribution

It provides the first comprehensive temperature-dependent relaxation rates for NV centers and introduces a new analytical model explaining high-temperature behavior via quasilocalized phonons.

Findings

Relaxation rates increase with temperature from 9 to 474 K.

Ab initio theory accurately reproduces the temperature dependence.

High-temperature relaxation dominated by two groups of quasilocalized phonons.

Abstract

Spin-lattice relaxation within the nitrogen-vacancy (NV) center's electronic ground-state spin triplet limits its coherence times, and thereby impacts its performance in quantum applications. We report measurements of the relaxation rates on the NV center's $|m_{s}=0\rangle \leftrightarrow |m_{s}=\pm 1\rangle$ and $|m_{s}=-1\rangle \leftrightarrow |m_{s}=+1\rangle$ transitions as a function of temperature from 9 to 474 K in high-purity samples. We show that the temperature dependencies of the rates are reproduced by an ab initio theory of Raman scattering due to second-order spin-phonon interactions, and we discuss the applicability of the theory to other spin systems. Using a novel analytical model based on these results, we suggest that the high-temperature behavior of NV spin-lattice relaxation is dominated by interactions with two groups of quasilocalized phonons centered at 68.2(17) and 167(12) meV.