Print Email Facebook Twitter Fluctuations in the electron system of a superconductor exposed to a photon flux Title Fluctuations in the electron system of a superconductor exposed to a photon flux Author De Visser, P.J. Baselmans, J.J.A. Bueno, J. Llombart, N. Klapwijk, T.M. Faculty Applied Sciences Department QN/Quantum Nanoscience Date 2014-02-05 Abstract In a superconductor, in which electrons are paired, the density of unpaired electrons should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the electron system of the superconductor to pair-breaking photons, microwave photons and varying temperatures. A large range in radiation power (at 1.54?THz) can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the electron system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48±8%) and showing an unprecedented detector sensitivity. At low radiation power, fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime. Subject physical sciencesapplied physicsoptical physics To reference this document use: http://resolver.tudelft.nl/uuid:378cbb77-4734-44de-a19f-cd737dfb97ec DOI https://doi.org/10.1038/ncomms4130 Publisher Nature Publishing Group ISSN 2041-1723 Source Nature Communications, 5, 2014 Part of collection Institutional Repository Document type journal article Rights (c) 2014 Macmillan PublishersThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License Files PDF Klapwijk_2014.pdf 563.84 KB Close viewer /islandora/object/uuid:378cbb77-4734-44de-a19f-cd737dfb97ec/datastream/OBJ/view