Magnetic impurities on superconductors lead to bound states within the superconducting gap, so called Yu-Shiba-Rusinov (YSR) states. They are parity protected, which enhances their lifetime, but makes it more difficult to excite them. Here, we realize the excitation of YSR states by microwaves facilitated by the tunnel coupling to another superconducting electrode in a scanning tunneling microscope (STM). We identify the excitation process through a family of anomalous microwave-assisted tunneling peaks originating from a second-order resonant Andreev process, in which the microwave excites the YSR state triggering a tunneling event transferring a total of two charges. We vary the amplitude and the frequency of the microwave to identify the energy threshold and the evolution of this excitation process. Our work sets an experimental basis and proof-of-principle for the manipulation of YSR states using microwaves with an outlook towards YSR qubits.
@article{arxiv.2303.13098,
title = {Microwave Excitation of Atomic Scale Superconducting Bound States},
author = {Janis Siebrecht and Haonan Huang and Piotr Kot and Robert Drost and Ciprian Padurariu and Björn Kubala and Joachim Ankerhold and Juan Carlos Cuevas and Christian R. Ast},
journal= {arXiv preprint arXiv:2303.13098},
year = {2023}
}
Comments
15 pages, 9 figures including supplementary information