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THU: Thursday Contributed Sessions
THU 13: Poster Session: Applications
THU 13.10: Poster
Thursday, September 11, 2025, 16:30–18:30, ZHG Foyer 1. OG
PTB Testbed for Quantum Key Distribution Metrology — •Ali Hreibi1, Mohsen Esmaeilzadeh2, Tara Liebisch3, and Stefan Kück4 — 1Ali.hreibi@ptb.de — 2mohsen .esmaeilzadeh@ptb.de — 3Tara .Liebisch@ptb.de — 4Stefan.Kueck@ptb.de
Various QKD systems, based on different protocols, have been developed for both free-space and optical fiber communication. However, despite significant progress over the past decades, achieving long-distance communication using single photons remains challenging. To mitigate rapid signal decay during transmission, technical compromises are often employed, which come at the expense of single-photon purity and overall communication fidelity, ultimately weakening the security provided by the laws of quantum mechanics. As a result, technical solutions are continuously being developed and implemented to prevent emerging attacks. We are developing various metrology techniques for calibrating and characterizing key components of QKD systems both in the laboratory and in field-deployed optical fibers. For example, to support QKD in daylight conditions, we are developing calibration methods for single-photon detectors operating with higher detection efficiencies at the Fraunhofer sodium D1 line, allowing for precise performance characterization under realistic environmental conditions. As well, we are developing techniques to characterize entangled photon sources using quantum state tomography and to multiplex different QKD signals in optical fiber.
Keywords: Quantum key distribution; Metrology; Optical fiber; Photon entanglement; Detector calibration