Single Photon Detectors for Quantum Computing

Optical quantum entanglement has emerged as a promising tool to solve many previously intractable problems in science and finds applications in signal processing, communication, and encryption. Quantum systems based on photons require optical detectors which are able to detect single photons, have a high photon to electron conversion gain, linear, low noise, and have a wide detection range. In order to be competitive with traditional computing systems in terms of size, weight, and power and to facilitate wider adoption the detectors should be low cost, scalable, and facilitate integration with the backend electronics. For these applications, single photon avalanche diodes (SPADs) are becoming more popular. They can be implemented in scalable formats using commercial silicon foundries where the cost per unit is low. However, these silicon SPADs suffer from higher noise and lower photon detection efficiency than other semiconducting materials. This paper we review an improved version of SPAD single photon detectors, perimeter gated SPAD (PGSPAD), which show improved noise performance and are suitable for quantum computing.