Extended Data Fig. 8: Calibration of the setup efficiency and calculation of the photon conversion efficiency.
From: Quantum correlations of spontaneous two-photon emission from a quantum dot
(a) All the optical elements used in the collection path. (b) Transmissions of the optical elements in the setup with a total efficiency of 0.034. We detect 496.58 K photon pairs per second under two-photon resonant excitation at π-pulse, with an excitation rate of 80 MHz. Taking into account our setup’s overall efficiency of 0.034 and an extraction efficiency of 0.8 for a typical micropillar device, we can deduce that 18.25 million photon pairs per second are generated in the cavity, corresponding to a generation efficiency of 18.25/80 = 0.228. By measuring the laser power of 0.77 nW at π-pulse, we estimate that approximately 26 photons were coupled into the cavity per single pulse. The photon conversion efficiency-defined as the probability of converting a single input photon from the laser pulse into a spontaneously emitted photon pair-is calculated as 0.228/26 = 0.877%.
