Heralded Emission Detection in Quantum Dot Solids under Twin-Photon Excitation

Abstract: Harnessing quantum correlations between photons is an emerging direction in optical spectroscopy, but experimental progress has thus far been limited to fluorescence-detected studies of molecular systems at room temperature. Here, we demonstrate heralded emission detection (HED) under continuous-wave (CW) entangled-photon excitation of near-infrared (NIR)-emitting colloidal III-V quantum dots (QDs) at low temperatures. We use superconducting nanowire single-photon detectors (SNSPDs) and large-area NIR avalanche photodiodes (APDs) to maximize the time resolution ($\sim$70 ps) and emission count rates ($\sim$2000 cps). To our knowledge, these results represent the first demonstration of HED in the solid state and establish NIR QDs as a bright, tunable model system with longer-lived coherences and integrability with optical cavities as an additional experimental control knob.