Berlin 2024 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 50: Superconductivity: Theory II
TT 50.5: Vortrag
Mittwoch, 20. März 2024, 16:00–16:15, H 3005
Nonequilibrium quasiparticle distribution in superconducting resonators: effect of pair-breaking photons — •Paul Benedikt Fischer1,2 and Gianluigi Catelani1,3 — 1JARA Institute for Quantum Information (PGI-11), Forschungszentrum Jülich, 52425 Jülich, Germany — 2JARA Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany — 3Quantum Research Center, Technology Innovation Institute, Abu Dhabi 9639, UAE
In the superconducting state, the presence of the finite gap in the excitation spectrum implies that the number of excitations (quasiparticles) is exponentially small at temperatures well below the critical one. Nevertheless, experiments at low temperature usually find a finite, non-negligible density of quasiparticles whose origin has been attributed to various non-equilibrium phenomena. Here, we investigate the role of photons with energy exceeding the pair-breaking threshold 2Δ as a possible source for these quasiparticles in superconducting resonators. Modeling the interacting system of quasiparticles, phonons, sub-gap and pair-breaking photons using a kinetic equation approach, we find analytical expressions for the quasiparticles’ density and their energy distribution. Applying our theory to measurements of quality factor as function of temperature and for various powers, we find they could be explained by assuming a small number of photons above the pair-breaking threshold.
Keywords: Nonequilibrium Superconductivity; Superconducting Quantum Optics; Light Matter Interaction