Browsing by Author "Lordi, V."

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    Physically motivated analytical expression for the temperature dependence of the zero-field splitting of the nitrogen-vacancy center in diamond
    (2023) Cambria, M. C.; Thiering, G.; Norambuena, A.; Dinani, H. T.; Gardill, A.; Kemeny, I.; Lordi, V.; Gali, A.; Maze, J. R.; Kolkowitz, S.
    The temperature dependence of the zero-field splitting (ZFS) between the vertical bar m(s) = 0 > and vertical bar m(s) = +/- 1 > levels of the nitrogen-vacancy (NV) center's electronic ground-state spin triplet can be used as a robust nanoscale thermometer in a broad range of environments. However, despite numerous measurements of this dependence in different temperature ranges, to our knowledge no analytical expression has been put forward that captures the scaling of the ZFS of the NV center across all relevant temperatures. Here we present a simple, analytical, and physically motivated expression for the temperature dependence of the NV center's ZFS that matches all experimental observations, in which the ZFS shifts in proportion to the occupation numbers of two representative phonon modes. In contrast to prior models our expression does not diverge outside the regions of fitting. We show that our model quantitatively matches experimental measurements of the ZFS from 15 to 500 K in single NV centers in ultrapure bulk diamond, and we compare our model and measurements to prior models and experimental data.
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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.