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MON: Monday Contributed Sessions
MON 20: Quantum Sensing and Decoherence: Contributed Session to Symposium II
MON 20.7: Talk
Monday, September 8, 2025, 18:00–18:15, ZHG009
Amplification and Detection of Single Itinerant Microwave Photons — Lukas Danner1,2, Ciprian Padurariu2, Max Hofheinz3, Joachim Ankerhold2, and •Björn Kubala1,2 — 1German Aerospace Center (DLR), Institute of Quantum Technologies, Ulm (Germany) — 2Institute for Complex Quantum Systems and IQST, University of Ulm, Ulm (Germany) — 3Institut Quantique, Université de Sherbrooke, Sherbrooke, Québec (Canada)
The detection of single microwave photons plays a crucial role in a wide range of technological applications using quantum microwaves. Standard readout techniques relying on linear amplification [1] add noise, limiting the chance of identifying single photons. Here, we propose schemes to amplify single itinerant mircowave photons using highly-nonlinear Josephson photonics devices [2]. These devices consist of a dc-voltage biased Josephson junction, connected in series with two microwave cavities. By tuning the dc voltage, various resonances can easily be accessed, such that, e.g., a Cooper pair tunneling through the junction enables a coherent transfer between one excitation in the first cavity and n excitations in the second cavity. Using a recently developed formalism [3], we describe how a single photon pulse is absorbed by the device to trigger the leakage of multiple photons from the second cavity that can subsequently be detected, and calculate performance parameters, such as detection probabilities and dark count rates.
[1] C. M. Caves, Phys. Rev. D 26, 1817 (1982)
[2] J. Leppäkangas et al., Phys. Rev. A 97, 013855 (2018)
[3] AH. Kiilerich and K. Mølmer, Phys. Rev. Lett. 123, 123604 (2019)
Keywords: Josephson junctions; quantum microwaves; single photon detector; superconductivity; tunneling