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Title Photon-assisted resonant Andreev reflections: Yu-Shiba-Rusinov and Majorana states
Authors Sergio Acero Gonzalez, Larissa Melischek, Olof Peters, Karsten Flensberg, Katharina J. Franke and Felix von Oppen
Journal Physical Review B
Vol. 102, 2020, pg. 045413


Abstract Photon-assisted tunneling frequently provides detailed information on the underlying charge-transfer process.In particular, the Tien-Gordon approach and its extensions predict that the sideband spacing in bias voltageis a direct fingerprint of the number of electrons transferred in a single tunneling event. Here, we analyzephoton-assisted tunneling into subgap states in superconductors in the limit of small temperatures and biasvoltages where tunneling is dominated by resonant Andreev processes and does not conform to the predictionsof simple Tien-Gordon theory. Our analysis is based on a systematic Keldysh calculation of the subgapconductance and provides a detailed analytical understanding of photon-assisted tunneling into subgap states,in excellent agreement with a recent experiment. We focus on tunneling from superconducting electrodes andinto Yu-Shiba-Rusinov states associated with magnetic impurities or adatoms, but we also explicitly extend ourresults to include normal-metal electrodes or other types of subgap states in superconductors. In particular, weargue that photon-assisted Andreev reflections provide a high-accuracy method to measure small but nonzeroenergies of subgap states which can be important for distinguishing conventional subgap states from Majoranabound states.



BibTeX entry
    @article{ AGP-2020:137,
      title = { Photon-assisted resonant Andreev reflections: Yu-Shiba-Rusinov and Majorana states },
      author = { Sergio Acero Gonzalez, Larissa Melischek, Olof Peters, Karsten Flensberg, Katharina J. Franke and Felix von Oppen },
      journal = { Physical Review B },
      volume = { 102 },
      year = { 2020 },
      pages = { 045413-- },
    }