Hidden Symmetry in Interacting-Quantum-Dot-Based Multiterminal Josephson Junctions

Peter Zalom; M. Žonda; T. Novotný

doi:10.1103/PhysRevLett.132.126505

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Hidden Symmetry in Interacting-Quantum-Dot-Based Multiterminal Josephson Junctions

Peter Zalom, M. Žonda, T. Novotný

DOI 10.1103/PhysRevLett.132.126505 · Physical Review Letters

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Abstract

We study a multiterminal Josephson junction based on an interacting quantum dot coupled to n superconducting BCS leads. Using an Anderson type model of a local level with an arbitrary on-site Coulomb repulsion, we uncover its surprising equivalence with an effective two-terminal junction with symmetric couplings to appropriately phase-biased leads. Regardless of the strength of the Coulomb interaction, this hidden symmetry enables us to apply well-established numerical and theoretical tools for exact evaluation of various physical quantities, and imposes strict relations among them. Focusing on three-terminal devices, we then demonstrate several phenomena such as the existence of the finite energy band crossings and superconducting transistor and diode effects, as well as current phase relation modulation.