Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 41: Quantum Dots and Point Contacts (joint session TT/HL)

HL 41.3: Vortrag

Donnerstag, 12. März 2026, 11:30–11:45, HSZ/0101

Dynamics of strong correlations of a hybrid quantum dot system with superconducting and ferromagnetic electrodes — •Antoni Jankiewicz, Kacper Wrześniewski, and Ireneusz Weymann — Institute of Spintronics and Quantum Information, Adam Mickiewicz University, Poznań, Poland

We theoretically explore the non-equilibrium dynamics of a quantum dot coupled to superconducting and ferromagnetic electrodes. This hybrid setup offers a rich platform to investigate the interplay between strong correlations, superconductivity, and ferromagnetism at the nanoscale. To perform the analysis we employ the numerical renormalization group and its time-dependent extension. These methods enable us to capture the subtle nature of dynamical quantum phase transitions induced by abrupt changes in Hamiltonian parameters, known as quantum quenches. Such transitions are crucial for understanding the stability and evolution of many-body states in response to external perturbations.

The aim of this work is to examine the competition between the superconducting pairing and the dot's spin. For that, we determine the time dependence of key observables, including the dot's spin and the on-dot pairing correlations. We demonstrate that these quantities reveal the competing character of correlations as they oscillate in counter-phase. Furthermore, we also analyze the dynamical quantum phase transitions in the system by determining the Loschmidt echo and the return function, which provide direct measures of the system's sensitivity to quenches.

Keywords: Dynamical quantum phase transitions; Numerical renormalization group