Optical probing of phononic properties of a tin-vacancy color center in diamond

The coherence characteristics of a tin-vacancy (SnV) color center in diamond are investigated through optical means, including linewidth broadening effects and coherent population trapping (CPT) between the ground-state orbital levels. Spectral analysis is required as due to the large spin-orbit splitting of the orbital ground states, thermalization between the ground states occurs at rates that are impractical to measure directly in the time domain. First, by implementing a temperature-dependent linewidth broadening measurement, including the challenging-to-measure D transition, phononic coupling coefficients are determined. These measurements are performed on an emitter with a lifetime-limited linewidth and atomlike properties, making the measurement representative for high-quality SnVs. Next, a CPT-type experiment is carried out to independently analyze thermal decoherence processes at 4 K. The spectral information is transformed into its conjugate variable time, providing picosecond resolution and revealing an orbital depolarization timescale of ∼ 30 ps . Consequences of the investigated dynamics are then used to estimate spin dephasing times limited by thermal effects.