Spin Dynamics from Atomistic Quantum Simulations

Optically active solid-state spin defects are promising candidates for quantum applications, however a unified theoretical framework to predict their spin dynamics at high temperatures is not yet available. Here, using Kubo linear–response theory, we derive expressions of spin-lattice and decoherence times $T_1$ and $T_2$ in terms of correlation functions of spin–lattice couplings. We then evaluate $T_1$ and $T_2$ from molecular dynamics and spin–lattice interaction time–series generated by state–of–the–art machine learning models trained on {\it ab–initio} data. Finally we measure $T_1$ times for the NV center in diamond and compare experimental and theoretical results, showing excellent agreement.