Quantum Dot Single Photon Sources Studied with Superconducting Single Photon Detectors

We report the observation of photon antibunching from a single, self-assembled InGaAs quantum dot (QD) at temperatures up to 135 K. The second-order intensity correlation, $g^{(2)}$ (0), is less than 0.260 $\pm$ 0.024 for temperatures up to 100 K. At 120 K, $g^{(2)}$(0) increases to about 0.471, which is slightly less than the second-order intensity correlation expected from two independent single emitters. In addition, we characterize the performance of a superconducting single photon detector (SSPD) based on a nanopatterned niobium nitride wire that exhibits 68 $\pm$ 3-ps timing jitter and less than 100-Hz dark count rate with a detection efficiency (DE) of up to 2% at 902 nm. This detector is used to measure spontaneous emission lifetimes of semiconductor quantum wells (QWs) emitting light at wavelengths of 935 and 1245 nm. The sensitivity to wavelengths longer than 1 $\mu$m and the Gaussian temporal response of this superconducting detector present clear advantages over the conventional detector technologies. We also use this detector to characterize the emission from a single InGaAs QD embedded in a micropillar cavity, measuring a spontaneous emission lifetime of 370 ps and a $g^{(2)}$ (0) of 0.24 $\pm$ 0.03.