Low-Temperature Photophysics of Single Nitrogen-Vacancy Centers in Diamond

Temperature dependence of photoluminescence intensity and spin contrast in nitrogen-vacancy centers

“…A temperature-dependent reduction in PL intensity and spin contrast was also reported in connection with NV charge state instabilities [18]. Further, spin mixing in the ES due to magnetic field [19,20] or crystal strain [21] was identified as another mechanism for loss of PL. The strain-related spin mixing at low temperature was found to be partially mitigated by application of a large magnetic bias field [15,20,22].…”

“…Further, spin mixing in the ES due to magnetic field [19,20] or crystal strain [21] was identified as another mechanism for loss of PL. The strain-related spin mixing at low temperature was found to be partially mitigated by application of a large magnetic bias field [15,20,22]. Because high PL intensity and spin contrast are essential for high-fidelity quantum readout and sensitive magnetometry, a complete picture of the NV photodynamics in the 10−100 K range is highly desirable.…”

“…Consequently, optical excitation into the E x branch is spin-conserving, while excitation into the E y branch will lead to spin mixing. In general, the spin mixing amplitudes i between the six levels depend on the strain magnitude and direction [21], as well as magnetic field alignment [19] and magnitude [20]. Therefore, the spin contrast is both strain and field-dependent.…”

“…To simulate the behavior of a chosen NV center, we feed our model with values obtained from a simultaneous fit of three sets of characterization measurements: (i) We use a measurement of the steady-state PL intensity as a function of magnetic field at base temperature (see Fig. 3(b, 4 K)) to obtain strain values and unintended misalignment of the bias field, fitting the minima in the PL at level anti-crossings [15,20]. (ii) We pick a set of 24 time-dependent PL traces (c.f.…”

Diamond surface engineering for molecular sensing with nitrogen—vacancy centers

“…This state has spin-triplet, orbital-doublet character (see other reviews for a detailed description 16,32,42,43 ) resulting in a fine structure containing six energy levels, which can be resolved under cryogenic conditions (T o 10 K). 44 At elevated temperatures, these orbitals undergo rapid averaging caused by the dynamic Jahn-Teller effect, 44,45 resulting in an effective three-level (spin-triplet) system at room temperature. In either case, decay from the NV excited state exhibits spindependent fluorescence (discussed in Section 2.2) that is exploited for spin-state readout in most NV-based quantum sensing schemes.…”