Single-photon detection in time-of-flight-depth imaging and quantum key distribution

Single-photon detectors play an increasing role in emerging application areas in quantum communication and low-light level depth imaging. The single-photon detector characteristics have a telling impact in system performance, and this presentation will examine the role of single-photon detectors in these important application areas. We will discuss the experimental system performance of GHz-clocked quantum key distribution systems focusing on issues of quantum bit error rate, net bit rate and transmission distance with different detector structures, concentrating on single-photon avalanche diode detectors, but also examining superconducting nanowire-based structures. The quantum key distribution system is designed to be environmentally robust and an examination of long-term system operation will be presented. The role of detector performance in photon-counting time-of-flight three-dimensional imaging will also be discussed. We will describe an existing experimental test bed system designed for kilometer ranging, and recent experimental results from field trials. The presentation will investigate the key trade-offs in data acquisition time, optical power levels and maximum range. In both examples, experimental demonstrations will be presented to explore future perspectives and design goals.