Fig. 2

Photo-physics of the single emitter introduced in Fig. 1. a Long autocorrelation measurements under excitation with a 675 nm laser (100 µW). Increasing the power of a coincident laser (532 nm, green arrow) suppresses the population of the intermediate/metastable states due to repumping of the emitter (see main text). The experimental data (points) are fitted (solid lines) using a four-level model. Error bars have been calculated based on the fitting to the autocorrelation data. b Reduction in the time constants τ₁ and τ₂ associated with the intermediate/metastable states (extracted from the fits in a; see Discussion in the main text) caused by increasing the power of the repumping 532 nm laser. c Simplified level structure of the emitter (see main text). The emitter possesses a ground state and excited state(s), as well as a fast-decaying intermediate and a long-lived metastable state. Radiative transitions are indicated by straight, solid arrows, repumping via the 532 nm laser is indicated by the green arrow, and fast and slow non-radiative transitions are indicated by dashed arrows. d The repumping causes a reduction in the laser power that is needed to saturate the emitter. e, f Fluorescence time trajectories of the emitter sampled into 100 ms bins, under excitation with 708 nm e or co-excitation with 708 and 532 nm lasers f, g. The power of the 708 nm laser was kept at 100 µW and the power of the 532 nm repumping laser was 0.5 and 10 µW in f and g, respectively. The corresponding histogram of the photon distribution at each excitation condition is shown on the right