Peter Zalom
Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18200 Praha 8, Czech Republic

Recent breakthroughs in experimental physics have paved the way for the creation of highly intricate nanoscale devices featuring three or more superconducting electrodes. These multi-terminal systems differ markedly from conventional two-lead Josephson junctions due to their heightened adjustability, a consequence of full superconducting phase control, which can be further exploited through the use of nanowires or carbon nanotubes in the central scattering region.

Commencing with an exploration of the fundamental principles underlying the Josephson effect in traditional two-terminal systems, we first delve into the characteristics of Josephson junctions based on nanowires or carbon nanotubes. We illustrate how an Anderson-type model, incorporating arbitrary onsite Coulomb repulsion, can accurately model such devices using the Numerical Renormalization Group (NRG) method [1]. Only then do we proceed to multi-terminal configurations, where we unveil their surprising equivalence to an effective two-terminal setup with symmetric couplings. Subsequently, with a focus on three-terminal devices, we demonstrate novel mechanisms for realizing superconducting transistors and diodes [2].

[1] P. Zalom, Rigorous Wilsonian Renormalization Group for impurity models with a spectral gap, arXiv 10.48550/arXiv.2307.07479 (2023), 2307.07479.
[2] P. Zalom, M. Žonda and T. Novotný, Hidden symmetry in interacting-quantum-dot-based multi-terminal Josephson junctions, arXiv 10.48550/arXiv.2310.02933 (2023), 2310.02933.