Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Quantum Dots, Quantum Wires, Point Contacts

TT 9.1: Invited Talk

Monday, March 12, 2018, 09:30–10:00, HFT-FT 101

Unconventional Superconductivity in Quantum-Dot Systems — •Stephan Weiss — Theoretische Physik, Universität Duisburg-Essen and CENIDE, 47048 Duisburg, Germany

The fermionic nature of electrons allows for four classes of superconducting correlations with definite symmetry in spin, space and frequency. Conventional (s-wave) superconductors accommodate even-frequency singlet Cooper pairs which are odd in spin and even in space and frequency. Odd-frequency triplet correlations generically arise in superconductor-ferromagnet heterostructures. Recently, we have suggested double quantum dots (DQDs) coupled to conventional superconductors in the presence of inhomogeneous magnetic fields as a model system exhibiting all four types of unconventional pairing. When reducing spatial degrees of freedom of the system further, i.e., to a single quantum dot, only odd-triplet and conventional superconducting correlations are allowed by symmetry. With the help of a diagrammatic real-time technique, the interplay of spin symmetry and superconductivity and its signatures in electronic transport, in particular current and zero frequency shot noise has been analyzed [2]. An applied magnetic field or attached ferromagnetic leads partially or fully reduce the spin symmetry, and odd-triplet superconducting correlations are generated.
B. Sothmann, S. Weiss, M. Governale, J. König, Phys. Rev. B 90, 220501 (2014).
S. Weiss and J. König, Phys. Rev. B 96, 064529 (2017).