Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: Quantum Coherence and Quantum Information Systems (joint session TT/DY)

TT 15.6: Talk

Tuesday, March 18, 2025, 11:00–11:15, H31

Of gyrators and anyons II - Gyrators — •Ram Mummadavarapu, Oleksiy Kashuba, and Roman-Pascal Riwar — Peter Grünberg Institut, Forschungszentrum Jülich, 52425 Jülich, Germany

In recent years, significant progress has been made in developing methods to create and control topological excitations in superconducting devices. Among these, the prediction of nontrivial Chern bands in conventional multiterminal Josephson junctions stands out as a particularly promising development. However, despite theoretical predictions, the experimental verification of the non-trivial Chern number remains an open challenge. Based on the realization that multiterminal junctions generically map on special gyrator networks hosting anyons (see also talk "Of gyrators and anyons I"), we here present circuit-specific band-engineering techniques to minimize parasitic anyon interactions. We show in particular how circular scattering in three-terminal quantum dot chains gives rise to a flat topological ground state, where disorder mitigates Chern number fluctuations and the quasiparticle continuum provides a work-around for known limitations to create nontrivial flat bands. Further band-engineering strategies are presented where the superconducting phase is scrambled either via parallelization or dissipative phase transitions.

Keywords: Topological flat bands; Circuit QED; Josephson effect; Band engineering; Andreev physics