Browsing by Author "Gardill, A."

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    State-dependent phonon-limited spin relaxation of nitrogen-vacancy centers
    (2021) Cambria, M. C.; Gardill, A.; Li, Y.; Norambuena, A.; Maze, J. R.; Kolkowitz, S.
    Understanding the limits to the spin coherence of the nitrogen-vacancy (NV) center in diamond is vital to realizing the full potential of this quantum system. We show that relaxation on the vertical bar m(s) = -1 > <-> vertical bar m(s) = +1 > transition occurs approximately twice as fast as relaxation on the vertical bar m(s) = 0 <-> vertical bar m(s) = +/- 1 > transitions under ambient conditions in native NVs in high-purity bulk diamond. The rates we observe are independent of NV concentration over four orders of magnitude, indicating they are limited by spin-phonon interactions. We find that the maximum theoretically achievable coherence time for an NV at 295 K is limited to 6.8(2) ms. Finally, we present a theoretical analysis of our results that suggests Orbach-like relaxation from quasilocalized phonons or contributions due to higher-order terms in the spin-phonon Hamiltonian are the dominant mechanism behind vertical bar m(s) = -1 > <-> vertical bar m(s) = +1 > relaxation, motivating future measurements of the temperature dependence of this relaxation rate.
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    Temperature-Dependent Spin-Lattice Relaxation of the Nitrogen-Vacancy Spin Triplet in Diamond
    (2023) Cambria, M. C.; Norambuena, A.; Dinani, H. T.; Thiering, G.; Gardill, A.; Kemeny, I.; Li, Y.; Lordi, V.; Gali, A.; Maze, J. R.; Kolkowitz, S.
    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 jms 1/4 0i & DIVIDE;-> jms 1/4 ⠂1i and jms 1/4 -1i & DIVIDE;-> jms 1/4 thorn 1i 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.