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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.

SUBMITTER: Estrada Saldana JC

PROVIDER: S-EPMC9042936 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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Excitations in a superconducting Coulombic energy gap.

Estrada Saldaña Juan Carlos JC Vekris Alexandros A Pavešić Luka L Krogstrup Peter P Žitko Rok R Grove-Rasmussen Kasper K Nygård Jesper J

Nature communications 20220426 1

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 superco ...[more]

PMID: 35473891

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