Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 73: Superconductivity: Tunneling and Josephson Junctions
TT 73.12: Talk
Thursday, March 12, 2026, 12:30–12:45, CHE/0089
Cooper quartets in frustrated Josephson junction arrays — •Erik Lennart Weerda1, Matteo Rizzi1,2, Michele Burrello3 und Olav Fredrik Syljuåsen4 — 1Forschungszentrum Jülich — 2Universität zu Köln — 3University of Pisa — 4University of Oslo
Josephson junction arrays in the shape of the dice lattice are the main candidates for a mesoscopic realization of superconductivity mediated by Cooper quartets of charge 4e. Here, we analyze numerical signatures of this exotic phase emerging when these superconducting arrays are frustrated by the insertion of 1/3 of a flux quantum per rhombic plaquette. Through the simulation of relaxation dynamics and two-dimensional infinite tensor network techniques, we examine the related classical XY model at finite temperature. We evaluate the characteristic properties of the supercurrent in this system, its correlation functions, and entropy. We also consider the effects of Josephson energy and flux disorder typical of Josephson junction arrays, and we address the role of charging energies in the full two-dimensional quantum model. Our results indicate that the peak of critical currents and temperatures at frustration 1/3 corresponds to a Cooper quartet phase, and the related superconducting-insulating phase transition is caused by the deconfinement of half-vortices.
Keywords: Josephson junction arrays