Can slow recombination in ordered superconductors explain the excess quasiparticle population?

Fuente: arXiv
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Hauptverfasser: Gurra, Eva, Bennett, Douglas A., Duff, Shannon M., Vissers, Michael R., Ullom, Joel N.
Format: Preprint
Veröffentlicht: 2025
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author Gurra, Eva
Bennett, Douglas A.
Duff, Shannon M.
Vissers, Michael R.
Ullom, Joel N.
author_facet Gurra, Eva
Bennett, Douglas A.
Duff, Shannon M.
Vissers, Michael R.
Ullom, Joel N.
contents An excess density of quasiparticles is widely observed in superconducting films. This excess causes performance degradation in a variety of superconducting devices, including decoherence in qubits. In this Letter, we evaluate the hypothesis of [1] that the quasiparticle excess is caused by anomalously slow recombination at low quasiparticle densities due to localization in sub-gap states. We probe the density of states in aluminum and niobium films using current-voltage measurements of tunnel junctions and extract upper bounds on the energy scales of the sub-gap states and gap smearing. With these parameters, we evaluate the recombination times predicted by [1] and find that slow recombination is not predicted to occur at observed quasiparticle densities in aluminumand niobium-based superconducting devices. These results suggest that the quasiparticle excess in ordered superconductors is primarily due to non-thermal sources of quasiparticle generation and not slow recombination.
format Preprint
id arxiv_https___arxiv_org_abs_2507_03217
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Can slow recombination in ordered superconductors explain the excess quasiparticle population?
Gurra, Eva
Bennett, Douglas A.
Duff, Shannon M.
Vissers, Michael R.
Ullom, Joel N.
Superconductivity
Quantum Physics
An excess density of quasiparticles is widely observed in superconducting films. This excess causes performance degradation in a variety of superconducting devices, including decoherence in qubits. In this Letter, we evaluate the hypothesis of [1] that the quasiparticle excess is caused by anomalously slow recombination at low quasiparticle densities due to localization in sub-gap states. We probe the density of states in aluminum and niobium films using current-voltage measurements of tunnel junctions and extract upper bounds on the energy scales of the sub-gap states and gap smearing. With these parameters, we evaluate the recombination times predicted by [1] and find that slow recombination is not predicted to occur at observed quasiparticle densities in aluminumand niobium-based superconducting devices. These results suggest that the quasiparticle excess in ordered superconductors is primarily due to non-thermal sources of quasiparticle generation and not slow recombination.
title Can slow recombination in ordered superconductors explain the excess quasiparticle population?
topic Superconductivity
Quantum Physics
url https://arxiv.org/abs/2507.03217