Regensburg 2019 – wissenschaftliches Programm
O 3.4: Vortrag
Montag, 1. April 2019, 11:15–11:30, H5
Probing coherence within tunneling events in a superconducting junction — •Piotr Kot1, Robert Drost1, Maximilian Uhl1, Joachim Ankerhold2, Alfredo Levy Yeyati3, Juan Carlos Cuevas3, and Christian R. Ast1 — 1Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 2Institut für Komplexe Quantensysteme and IQST, Ulm, Germany — 3Departamento de Fisica Teorica de la Materia Condensada, Madrid, Spain
Using a superconducting tunnel junction irradiated by microwaves, we study the coherent and incoherent processes in photon-assisted tunneling. While our junction operates within the dynamical Coulomb blockade regime that involves incoherent tunneling between events, we find coherent processes within a tunneling event that can be tuned by varying the microwave intensity. We find that higher order charge transfers can not necessarily be related to the simple Tien-Gordon equation. Taking the experiment to the limit, we are able to measure coherent tunneling processes involving photons up to 50th order that do not quench superconductivity but rather distribute the spectral weight accordingly. In addition, in the high transmission regime coherence within Andreev reflections is demonstrated. Our finding suggest new avenues of studying higher order charge processes in a single junction.