SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Poster Session: Superconductivity
TT 5.21: Poster
Montag, 27. September 2021, 13:30–16:00, P
Emission of photon multiplets by a dc-biased superconducting circuit — •Björn Kubala1,2, Gerbold Menard3, Ambroise Peugeot3, Ciprian Padurariu2, Chloe Rolland3, Zubair Iftikhar3, Yuri Mukharsky3, Carles Altimiras3, Helene le Sueur3, Philippe Joyez3, Denis Vion3, Patrice Roche3, Daniel Esteve3, Joachim Ankerhold2, and Fabien Portier3 — 1Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany — 2ICQ and IQST, Ulm University, Germany — 3SPEC, CEA Paris-Saclay, France
We show experimentally that a dc-biased Josephson junction in series with a high-impedance microwave resonator can emit up to k=6 photons simultaneously for each Cooper pair tunneling through the junction. Our resonator is made of a simple micro-fabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97 kΩ characteristic impedance, corresponding to an effective fine-structure constant, α ∼ 1. Measuring the second order correlation function of the emission from the resonator allows computing the Fano factor F of the emitted photons, found to coincide with the naive prediction F=k in the weak driving regime. At higher emission, the feedback of the population of the resonator on the emission dynamics yields a non-monotonous behavior, hallmark of parametric transitions. Results are found in quantitative agreement with our theoretical predictions. This simple scheme highlights the ability of superconducting devices operating in the microwave domain to reach strong-coupling regimes of matter-light coupling inaccessible to conventional quantum optics experiments in the visible domain.