Nuclear spin relaxation in solid state defect quantum bits via electron-phonon coupling in their optical excited statehttps://hdl.handle.net/21.15109/ARP/O4CEI6Thiering, GergőGali, ÁdámARP2025-08-072025-08-07T16:35:38ZOptically accessible solid state defect spins serve as a primary platform for quantum information processing, where precise control of the electron spin and ancillary nuclear spins is essential for operation. Using the nitrogen-vacancy (NV) color center in diamond as an example, we employ a combined group theory and density functional theory study to demonstrate that spin-lattice relaxation of the $^{14}$N nuclear spin is significantly enhanced due to strong entanglement with orbital degrees of freedom in the $|^3E\rangle$ optical excited state of the defect. This mechanism is common to other solid-state defect nuclear spins with similar optical excited states. Additionally, we propose a straightforward and versatile \textit{ab initio} scheme for predicting orbital-dependent spin Hamiltonians for trigonal defects exhibiting orbital degeneracy.PhysicsVASPJahn-Teller effectDiamondNV center(D) Zero-field splitting(A) Hyperfine coupling(P) Nuclear quadropular couplingPoint defectRabi oscillationFermi's Golden Ruleab-initiofirst principlesDFTluminescencequbitspin coherencespin relaxationG. Thiering, A. Gali: arXiv:2402.19418 [quant-ph] (2025), doi, 10.48550/arXiv.2402.19418, https://doi.org/10.48550/arXiv.2402.194182025-08-07Thiering, Gergő2025-08-01VASP INCAR, OUTCAR, vasprun.xml, POSCAR etc. input/output files.CC BY 4.0