The physics of a quantum impurity in a superconductor is governed by the fermionic parity and spin of the two possible ground states, doublet or singlet, and their corresponding Yu-Shiba-Rusinov subgap excitations. After an introduction about their role in hybrid superconductor/semiconductor nanowires containing quantum dots , I will focus on semiconducting nanowires fully wrapped by a superconductor where an external magnetic flux gives rise to new regimes hitherto unexplored .
In the second part, I will discuss the physics of a superconducting qubit whose Josephson energy is governed by a fully tunable quantum dot. Specifically, a circuit QED setup allows to probe both its ground state and quasiparticle dynamics, resulting in, arguably, the most in-depth experimental study of a superconducting quantum impurity to date . These results hold promise for realizing Andreev qubits with long parity lifetimes.
 Lee et al Phys. Rev. Lett. 109, 186802 (2012); Žitko et al, Phys. Rev. B 91, 045441 (2015); Lee et al, Nature Nanotech., 9, 79-84 (2014).  Valentini et al, Science 373, 82-88 (2021); Escribano et al, Phys. Rev. B 105, 045418 (2022).  Bargerbos et al arXiv:2202.12754. PRX Quantum, in press.
Note the unusual day of the week. The seminar is presential with parallel zoom stream: https://zoom.us/j/98286706234?pwd=bm1JUFVYcTJkaVl1VU55L0FiWDRIUT09
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