Dresden 2026 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 85: Superconductivity: Yu-Shiba-Rusinov and Andreev Physics
TT 85.8: Vortrag
Donnerstag, 12. März 2026, 17:00–17:15, CHE/0089
Assessing effective models of double quantum dot Andreev molecules — •Kacper Wrześniewski1, Peter Zalom2, Tomasz Tomáš Novotný3, and Ireneusz Weymann1 — 1Institute of Spintronics and Quantum Information, Faculty of Physics and Astronomy, Adam Mickiewicz University in Poznań, Poland — 2Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic — 3Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
We investigate the phase diagram of a parallel double-quantum-dot Andreev molecule, in which the two quantum dots are coupled to a common superconducting lead. Using the numerical renormalization group (NRG) method, we analyze the evolution of the ground state across a broad parameter space, including level detuning, superconducting gap size, lead couplings, and interdot hopping. The resulting phase diagrams exhibit singlet, doublet, and a relatively uncommon triplet ground state, the latter serving as a clear signature of strong lead-mediated interactions between the quantum dots.
To evaluate the reliability of simplified theoretical descriptions, we benchmark the applicability of several effective models, including the atomic limit and zero-bandwidth approximations. Our results reveal notable limitations of these approaches: with the exception of the extended zero-bandwidth approximation, the effective models fail to reproduce the triplet ground state. These findings provide valuable guidance for interpreting experimental data and for the design of superconducting devices based on quantum dots.
Keywords: quantum dots; Andreev bound states