Excitation of Single Quasiparticles in a Small Superconducting Al Island Connected to Normal-Metal Leads by Tunnel Junctions

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2013
Major/Subject
Mcode
Degree programme
Language
en
Pages
147001/1-5
Series
Physical Review Letters, Volume 111, Issue 14
Abstract
We investigate the dynamics of individual quasiparticle excitations on a small superconducting aluminum island connected to normal metallic leads by tunnel junctions. We find the island to be free of excitations within the measurement resolution. This allows us to show that the residual heating, which typically limits experiments on superconductors, has an ultralow value of less than 0.1 aW. By injecting electrons with a periodic gate voltage, we probe electron-phonon interaction and relaxation down to a single quasiparticle excitation pair, with a measured recombination rate of 16 kHz. Our experiment yields a strong test of BCS theory in aluminum as the results are consistent with it without free parameters.
Description
Keywords
individual quasiparticle excitations, small superconducting aluminum islands, metallic leads, tunnel junctions, superconductors
Other note
Citation
Maisi, V. F. & Lotkhov, S. V. & Kemppinen, A. & Heimes, A. & Muhonen, J. T. & Pekola, Jukka. 2013. Excitation of Single Quasiparticles in a Small Superconducting Al Island Connected to Normal-Metal Leads by Tunnel Junctions. Physical Review Letters. Volume 111, Issue 14. P. 147001/1-5. ISSN 0031-9007 (printed). DOI: 10.1103/physrevlett.111.147001.