Josephson radiation and shot noise of a semiconductor nanowire junction
David Van Woerkom (TU Delft - QRD/Kouwenhoven Lab)
A. Proutski (TU Delft - QRD/Kouwenhoven Lab)
Ruben J.J. Van Gulik (TU Delft - QN/Quantum Transport, TU Delft - QRD/Kouwenhoven Lab)
Diana Car (Eindhoven University of Technology)
SR Plissard (Eindhoven University of Technology)
EPAM Bakkers (Eindhoven University of Technology, TU Delft - QN/Bakkers Lab)
L.P. Kouwenhoven (TU Delft - QRD/Kouwenhoven Lab)
A. Geresdi (TU Delft - QRD/Geresdi Lab)
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Abstract
We measured the Josephson radiation emitted by an InSb semiconductor nanowire junction utilizing photon-assisted quasiparticle tunneling in an ac-coupled superconducting tunnel junction. We quantify the action of the local microwave environment by evaluating the frequency dependence of the inelastic Cooper-pair tunneling of the nanowire junction and find the zero-frequency impedance Z(0)=492Ω with a cutoff frequency of f0=33.1GHz. We extract a circuit coupling efficiency of η≈0.1 and a detector quantum efficiency approaching unity in the high-frequency limit. In addition to the Josephson radiation, we identify a shot noise contribution with a Fano factor F≈1, consistently with the presence of single electron states in the nanowire channel.