Investigation of Stark shift and charge noise on a centrosymmetric diamond defect

Quantum emitters in diamond are among the most promising systems for the realization of optically accessible qubits in the solid state. Group IV-vacancy defect centers in particular have attracted great interest owing to their inversion symmetry, which is expected to provide coherent and stable optical interfaces.
Here we investigate the effect of an external electric field on the optical transition of a single tin-vacancy (SnV) center in diamond. Our study reveals the absence of a permanent electric dipole with a suppressed polarizability of the emitter, more than 4 orders of magnitude lower than for an NV center. This is the first direct demonstration of the inversion symmetry protection of a Group IV-vacancy defect in diamond from charge noise. Moreover, we show that by modulating the SnV electric-field-induced dipole we can use the SnV optical linewidth as a nanoscale probe to quantify electric field noise at its location. To gain further insight on the effect of the electric field noise, we also probe the optical transition at different timescales. This allows to resolve the individual spectral jumps of the transition, and to measure the homogeneous linewidth of the emitter without spectral diffusion effects.