Freiburg 2024 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 7: Quantum Communication I
Q 7.8: Vortrag
Montag, 11. März 2024, 12:45–13:00, HS 3219
Clock recovery with single photon clicks for satellite QKD — •Conrad Rößler1,2, Bastian Hacker1,2, Kevin Günthner1,2, and Christoph Marquardt1,2 — 1Lehrstuhl für Optische Quantentechnologien, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen, Germany — 2Max Planck Institute for the Science of Light, Staudtstr. 2, 91058 Erlangen, Germany
While Quantum Key Distribution (QKD) offers an information theoretical secure way to exchange cryptographic keys, its experimental implementation poses technical challenges, especially in satellite QKD. Since QKD sources work with very weak signals in order to profit from the quantum mechanical no-cloning theorem, the high loss experienced in satellite QKD is particularly disruptive for these fragile states. One way to overcome this is to increase the modulation and sent symbol rate. However, still only very few of these fast modulated signals will arrive at the receiver. For successful key exchange, one must map each of the received states correctly onto the corresponding sent state, which is especially difficult for high rates. Since resources at the satellite are usually limited, the most obvious solution of storing every sent state at the sender for a long time is not practical. Thus, a fast clock recovery is critical in order to allow processing of the received states at runtime. We present our clock recovery algorithm, based on single photon clicks received from reference signal time multiplexed with the quantum states. With this technique, we achieve below nanosecond accuracy within less than a second.
Keywords: Quantum Key Distribution; Epoch folding; Clock recovery