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Updated: Sep 25, 2025
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Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
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Excitations in a superconducting Coulombic energy gap.
Juan Carlos Estrada Saldaña1, Alexandros Vekris2,3, Luka Pavešić4,5
1Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark. juan.saldana@nbi.ku.dk.
Nature Communications
|April 27, 2022
Summary
Strong Coulomb repulsion in superconductors alters quantum dot excitations, breaking electron-hole symmetry and changing many-body states. This impacts potential applications in topological superconducting qubits.
Area of Science:
- Condensed Matter Physics
- Quantum Information Science
Background:
- Cooper pairing and Coulomb repulsion create distinct energy gaps in superconductors and Mott insulators.
- Yu-Shiba-Rusinov excitations, characterized by electron-hole symmetry, arise when superconductors interact with quantum dots.
Purpose of the Study:
- Investigate the behavior of Yu-Shiba-Rusinov excitations under strong Coulomb repulsion in a superconductor.
- Understand the impact of Coulomb repulsion on many-body states and excitation symmetry.
Main Methods:
- Coupling a quantum dot to a superconducting island with tunable Coulomb repulsion.
- Analyzing the resulting many-body states and excitation properties.
Main Results:
- Strong Coulomb repulsion transforms the singlet many-body state into a two-body state.
- Electron-hole energy symmetry of the excitations is broken by strong Coulomb repulsion.
- Excitations lose their Yu-Shiba-Rusinov character under strong Coulomb repulsion.
Conclusions:
- Coulomb repulsion fundamentally alters the nature of excitations at the superconductor-quantum dot interface.
- Findings are crucial for understanding and developing topological superconducting qubits and multi-channel impurity models.
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