Berlin 2024 – scientific programme
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QI: Fachverband Quanteninformation
QI 3: Quantum Communication
QI 3.9: Talk
Monday, March 18, 2024, 11:45–12:00, HFT-TA 441
Microwave quantum tokens with time multiplexing — •Florian Fesquet1,2, Valentin Weidemann1,2, Fabian Kronowetter1,2,3, Michael Renger1,2, Wun K. Yam1,2, Simon Gandorfer1,2, Achim Marx1, Rudolf Gross1,2,4, and Kirill G. Fedorov1,2,4 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — 2School of Natural Sciences, Technische Universität München, 85748 Garching, Germany — 3Rohde & Schwarz GmbH & Co. KG, 81671 Munich, Germany — 4Munich Center for Quantum Science and Technology, 80799 Munich, Germany
Quantum key distribution (QKD) holds the promise of delivering unconditionally secure distribution of classical keys between remote parties. So far, its implementation in the microwave regime, frequency-compatible with superconducting quantum circuits, has been missing. Here, we present a realization of a continuous-variable (CV) QKD protocol using propagating displaced squeezed microwave states and demonstrate an experimental unconditional security. We show that secret key rates can be increased by adding finite trusted noise to the preparation side and by exploiting the time multiplexing approach. Our results indicate feasibility of secure microwave quantum communication under cryogenic (up to 1200 meters) and open-air (up to 80 meters) conditions. Finally, we discuss coupling of the squeezed microwave states to spin ensembles, enabling long-term quantum memories for resulting quantum tokens.
Keywords: Quantum communication; Quantum networks; Secure communication; Quantum cryptography; Quantum tokens