Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: New Methods and Developments I: Scanning Probe Techniques

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 50^th 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.