Towards free-space quantum key distribution with a 2D single-photon sensor

Applications of quantum key distribution are becoming more diverse due to the increase in interest in the secure key sharing protocol. Transmission through free-space channels has risen in popularity in recent years, primarily due to global coverage using satellite platforms. However, free-space channels come with challenges that need to be addressed, such as; diffraction loss, background noise, pointing-and-tracking, and atmospheric aberration. Novel design and use of state-of-the-art detector technologies in quantum receivers can help alleviate these difficulties. This paper presents and discusses the implementation of 2D single-photon sensor technology for free-space quantum key distribution. We present an experimental method that utilizes independent single-photon avalanche diode pixel read-out to reduce background noise contributions while simultaneously increasing optical field-of-view. Finally, we show and discuss single-photon level beaconing capabilities for pointing and tracking.