Excitations in a superconducting Coulombic energy gap
Abstract
Cooper pairing and Coulomb repulsion are antagonists, producing distinct energy gaps in superconductors and Mott insulators. When a superconductor exchanges unpaired electrons with a quantum dot, its gap is populated by a pair of electron-hole symmetric Yu-Shiba-Rusinov excitations between doublet and singlet many-body states. The fate of these excitations in the presence of a strong Coulomb repulsion in the superconductor is unknown, but of importance in applications such as topological superconducting qubits and multi-channel impurity models. Here we couple a quantum dot to a superconducting island with a tunable Coulomb repulsion. We show that a strong Coulomb repulsion changes the singlet many-body state into a two-body state. It also breaks the electron-hole energy symmetry of the excitations, which thereby lose their Yu-Shiba-Rusinov character.
Keywords
Cite
@article{arxiv.2101.10794,
title = {Excitations in a superconducting Coulombic energy gap},
author = {Juan Carlos Estrada Saldaña and Alexandros Vekris and Luka Pavešič and Peter Krogstrup and Rok Žitko and Kasper Grove-Rasmussen and Jesper Nygård},
journal= {arXiv preprint arXiv:2101.10794},
year = {2022}
}
Comments
Supplementary Information available as an ancillary file with this submission. Raw experimental data available at https://doi.org/10.17894/ucph.e17975c9-c12c-412b-b046-aca7526cb8ed