The phonon-modulated Jahn-Teller distortion of the nitrogen vacancy center in diamond.

The negatively charged nitrogen vacancy (NV) center in diamond is an optically accessible material defect with a unique combination of spin and optical properties that has attracted interest in quantum-information sciences and as a design candidate for nanoscale quantum sensors. Here, we present time-resolved nonlinear optical spectroscopy measurements, conducted with ultrabroadband laser pulses, that reveal strong modulation of the excited-state by the longitudinal optical (LO) phonon of the diamond lattice. The LO phonon and its overtones geometrically distort neighboring NV centers, driving long lived (3.5 ps) excited state relaxation of coupled NV centers after the initial excitation and ultrafast (<150 fs) decay of the Jahn-Teller distortion. These observations elevate the LO phonon to an important tuning mode of the Jahn-Teller conical intersection and help resolve previous spectroscopy experiments that noted longer-lived excited-state dynamics.