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TT: Fachverband Tiefe Temperaturen

TT 20: Quantum Dots and Quantum Wires (joint session TT/HL)

TT 20.4: Talk

Monday, March 18, 2024, 17:30–17:45, H 3007

Multi-terminal interacting-quantum-dot-based devices — •Peter Zalom — Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18200 Praha 8, Czech Republic

Recent breakthroughs in experimental physics pave the way for the creation of intricate nanoscale devices featuring three or more superconducting electrodes. Such multi-terminal systems differ markedly from conventional two-lead Josephson junctions due to the supercurrent distribution into the constituent terminals. Exerting full phase-control leads then to a multitude of practical applications.

In this talk, we explore the potential for using nanowires or carbon nanotubes in the central scattering region to enhance the existing functionalities via the underlying quantum phase transitions. Our findings, as elucidated in [1], lay the foundation for purely phase-controlled superconducting transistor and diode effects in three-terminal systems even in the absence of inter-lead couplings. Proceeding with more complex architectures requires, however, development of new Numerical Renormalization Group (NRG) methods to accommodate arbitrary gapped tunneling densities of states. This critical development, recently detailed in Ref. [2], significantly expands our theoretical understanding, particularly in devices incorporating topological effects.

[1] P. Zalom, M. Žonda and T. Novotný, arXiv:2310.02933 (2023).

[2] P. Zalom, Phys. Rev. B 108 (2023) 195123.

Keywords: Numerical Renormalization Group; superconducting transistor; superconducting diode; multi-terminal devices