**Summary **

An essential aspect of a quantum channel is the detection and analysis of quantum signals in the form of photons. For most free-space applications, the photons are polarization encoded, e.g. by assigning the ‘0’ to horizontally polarized photons and ‘1’ to vertically polarized photons. However, where the geometric reference is not constant at all times – such as links to hand-held devices or aircraft – polarization encoding leads to increased error. For these situations, time-bin encoding offers a promising robust solution. In this approach, time photon represents ‘0’ or ‘1’ depending on its detection in one of two time windows. Just like in the case of polarization encoding, where a photon can be in a superposition of vertical and horizontal polarization, a time-bin encoded photon can be in a superposition of being in the first and the second time window. Additionaly, quantum signals can be relatively easily converted between being polarization and time-bin encoded.

In this project, we jointly develop a quantum receiver with short time delay and high timing resolution that is optimized to handle time-bin encoded quantum signals. By combining our team’s expertise in free-space quantum receivers with a new detector array technology developed by Dr. Serge Charlebois and Jean-Francois Pratte of the University of Sherbrooke and by introducing new capabilities for integrated free-space time-bin encoding with high timing resolution detection, we expect to achieve state-of-the-art performance for quantum signal receiver technology. Such high-speed devices will open new doors for a variety of applications including daylight and continuous variable quantum key distribution, quantum sensing, imaging and LIDAR, and fundamental science tests.

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