Single-photon detectors, such as Avalanche Photo Diodes (APDs), have a great importance in many fields, including quantum key distribution, laser ranging, florescence microscopy, etc. Unfortunately, APDs operated in Geiger... [ view full abstract ]
Single-photon detectors, such as Avalanche Photo Diodes (APDs), have a great importance in many fields, including quantum key distribution, laser ranging, florescence microscopy, etc. Unfortunately, APDs operated in Geiger mode, suffer from several non-ideal behaviours of particular interest is the Afterpulse effect. Afterpulsing has different implications, depending on the intended application of the detector (fluorescence microscopy, quantum key distribution, etc.). Afterpulsing can adversely affects any application that measures the number or timing of detection events. Especially in quantum key distribution system, afterpulsing can adversely affect security and hence part of the security analysis.
Several studies have tried to link the afterpulsing behaviour to fundamental semiconductor physics. However, most of these studies have conflicting results. Some studies link the behavior to the distribution of discrete energy levels, while others formulate laws assuming continuous/quasi-continuous energy levels. Other studies posit "deep levels" while still more are based on Arrhenius law. The above works are inconstant with each other and are fundamentally different with conflicting results. To resolve the conflicts raised by these works and analyze the universality of these various theoretical models, we compare different commercial products against the canonical models proposed by previous studies. We show that different individual detectors - even if identical in type, make, brand, etc. - behave according to fundamentally different mathematical models. This lack of universality of the standard mathematical models of afterpulsing indicates that these studies can no longer be considered as of importance for semiconductor physics. We also report the presence of high-order afterpulses that are not accounted for in any of the standard models.
Further, to demonstrate that the ``Dead time'' is a misnomer because the detector is not completely dead/inactive instead it exhibits a reduced detection efficiency, we use the cross-correlation function to investigate the so-called "Dead time'' region of various detectors.
Quantum sensors and quantum metrology , Quantum communication , Quantum optics and non-classical light sources
