Photophysics of chromium-related diamond single-photon emitters

A detailed study of the photophysical properties of several chromium-related color centers produced within chemical vapor deposition diamond is presented. These emitters show narrow luminescence lines in the range of 740-770 nm. Single-photon emission was verified with continuous and pulsed excitation with detected emission rates at saturation in the range of (2-3) × 10⁶ counts/s, while direct lifetime measurements reveal excited state lifetimes for the distinct centers ranging 1-14 ns. In addition, a number of quantum emitters demonstrate two-level behavior with no bunching present in the second-order correlation function. The three-level systems revealed typically photoluminescence lines with width half-maximum of ~4 nm while the two-level emitters have full width half-maximum of ~10 nm at room temperature. In addition, the quantum efficiency of the two-level system was measured to be four times higher than that of the three-level system.