Fig. 3: Measurement of photon statistics for different excitation schemes.

We determine the second-order autocorrelation function by measuring coincidences at the output of a 50:50 beam splitter for excitation using (a) above-band-gap, (b) LA-phonon-assisted, (c) resonance #1, and (d) resonance #2. It is evident that the correlation peaks measured for above-band-gap excitation as well as at resonance #1 are broadened compared to resonance #2 and LA-phonon-assisted excitation, indicating an increased excited-state lifetime for these resonances. The values g⁽²⁾(τ = 0) are determined by calculating the average area beneath the correlation peaks at τ ≠ 0 (highlighted in red) and comparing it to the area around τ = 0 (highlighted in green) in a window of Δt = 3 ns as shown in the insets. All excitation schemes show g⁽²⁾(τ = 0) < 0.5, thus indicating mainly single-photon emission. Note that a peak is present every 25 ns as a result of the active demultiplexing.