Sean Lourette, Andrey Jarmola, Victor M. Acosta, A. Glen Birdwell, Dmitry Budker, Marcus W. Doherty, Tony Ivanov, and Vladimir S. Malinovsky (Phys. Rev. Applied 19, 064084 – Published 30 June, 2023)
We measure electron- and nuclear-spin transition frequencies in the ground state of nitrogen-vacancy (N-V) centers in diamond for two nitrogen isotopes (14N-V and 15N-V) over temperatures ranging from 77 to 400 K. Measurements are performed using Ramsey interferometry and direct optical readout of the nuclear and electron spins. We extract coupling parameters Q (for 14N-V), D, A∥, A⊥, and γe/γn, and their temperature dependences for both isotopes. The temperature dependences of the nuclear-spin transitions within the ms=0 spin manifold near room temperature are found to be 0.52(1) ppm/K for 14N-V (|mI=−1⟩↔|mI=+1⟩) and −1.1(1) ppm/K for 15N-V (|mI=−1/2⟩↔|mI=+1/2⟩). An isotopic shift in the zero-field splitting parameter D between 14N-Vand 15N-V is measured to be ∼120 kHz. Residual transverse magnetic fields are observed to shift the nuclear-spin transition frequencies, especially for 15N-V. We have precisely determined the set of parameters relevant for the development of nuclear-spin-based diamond quantum sensors with greatly reduced sensitivity to environmental factors.