Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 31: Quantum Communication IV
Q 31.7: Talk
Wednesday, March 13, 2024, 12:30–12:45, HS 3219
Deployment and optimization of high-dimensional QKD on a 1.7 km free-space link — •Karolina Paciorek1, Christopher Spiess1,2, Sarika Mishra1, and Fabian Steinlechner1,2 — 1Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Strasse 7, Jena 07745, Germany — 2Friedrich Schiller University, Institute of Applied Physics, Abbe Center of Photonics, Albert-Einstein-Strasse 15, Jena 07745, Germany
Quantum Key Distribution (QKD) is a method for establishing a secure encryption key using a quantum optical sender, a transmission link, and an optical receiver. When QKD is implemented over short distances with low losses, such as in data centers or intercity links, then the maximum secure key rate is typically limited by saturation of the single-photon detectors at the receiver. To overcome this limitation, high-dimensional QKD protocols can be implemented.
High-dimensional QKD protocols enable encoding more information into one photon, which enables operation at photon rates that no longer saturate the detectors. We show this at the example of a weak coherent source in a time-phase encoding scheme. Furthermore, we demonstrate the transfer of key material over a 1.7 km intercity free-space link. Our demonstration is accompanied by finite-key analysis together with an extensive parameter optimization in experiment and simulations to maximize the key rate. Our results show that high-dimensional QKD with weak coherent sources is a promising avenue towards versatile communication scenarios, including areas with difficult access such as rapidly changing metropolitan spaces or in satellite communication.
Keywords: Quantum Key Distribution (QKD); High-dimensional QKD; Free-space link; Weak coherent sources; Key rate optimization