Quasiparticle spectroscopy in technologically relevant niobium using London penetration depth measurements: experiment and theory
Abstrak
The London penetration depth, $\lambda(T)$ , was measured in various forms of niobium, including foils, thin films, single crystals, and samples from superconducting radio-frequency (SRF) cavities. We observed a significant difference in $\lambda(T)$ at low temperatures, $T \lt T_\mathrm{c}/3$ , due to low-energy quasiparticles. In particular, an unusual downturn of $\lambda(T)$ on cooling in the SRF cavity samples required to take into account deep in-gap bound states. Theoretical modeling using the generalized Dynes density of states shows that such in-gap states lead to a downturn or a peak in $\lambda(T)$ upon cooling. Combined, experimental and theoretical findings provide a method for detecting two-level systems or states related to magnetic impurities in the bulk of niobium. This result is particularly relevant for the quantum informatics sciences technologies used in qubits and circuit quantum electrodynamics architecture based on SRF cavities.
Topik & Kata Kunci
Penulis (13)
Sunil Ghimire
Kamal R Joshi
Amlan Datta
Aidan Goerdt
Makariy A Tanatar
Deborah Schlagel
Matthew J Kramer
Jayss Marshall
Cameron J Kopas
Joshua Y Mutus
Alexander Romanenko
Anna Grassellino
Ruslan Prozorov
Akses Cepat
- Tahun Terbit
- 2024
- Sumber Database
- DOAJ
- DOI
- 10.1088/2633-4356/ad8c0c
- Akses
- Open Access ✓