Freiburg 2019 – wissenschaftliches Programm

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FM: Fall Meeting

FM 63: Poster: Enabling Technologies: Quantum Materials, Quantum Dots, Quantum Wires, Point Contacts and Superconducting Systems

FM 63.10: Poster

Mittwoch, 25. September 2019, 16:30–18:30, Tents

Tunneling between isolated quasiparticle levels via Cooper pair splitting in an atomic contact — •Haonan Huang¹, Jacob Senkpiel¹, Robert Drost¹, Ciprian Padurariu², Simon Dambach², Björn Kubala², Juan Carlos Cuevas³, Alfredo Levy Yeyati³, Joachim Ankerhold², Christian R. Ast¹, and Klaus Kern^1,4 — ¹MPI für Festkörperforschung, Germany — ²Institut für komplexe Quantensysteme, Universität Ulm, Germany — ³Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Spain — ⁴EPFL, Switzerland

Tunneling processes between discrete levels have been extensively studied in double quantum dots typically with the size of hundreds of nanometers. Scaling down these devices to the atomic scale remains, however, challenging. One alternative approach is to use scanning tunneling microscopy to build atomic sized tunnel junctions, and use the Yu-Shiba-Rusinov (YSR) states, quasiparticle levels generated by magnetic atoms on a superconductor, as discrete levels. With a scanning tunneling microscope at 15mK, we study the tunneling processes between a YSR state on the tip and a YSR state on the sample, which we call Shiba-Shiba tunneling. While Shiba-Shiba tunneling inherits features of tunneling between discrete levels, the physics is much richer because of the Cooper pair splitting processes involved. Depending on the energy of the Shiba state, four regimes with distinctly different behavior of Shiba-Shiba tunneling exist. This results in different interactions with the environment, which may shed light on the coherence and entanglement of the quasiparticles during tunneling processes.