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Published on: August 2, 2019
Spectrum of Andreev bound states in a molecule embedded inside a microwave-excited superconducting junction
Jonas Sköldberg1, Tomas Löfwander, Vitaly S Shumeiko
1Department of Microtechnology and Nanoscience--MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
Abstract:
Nondissipative Josephson current through nanoscale superconducting constrictions is carried by spectroscopically sharp energy states, the so-called Andreev states. Although theoretically predicted almost 40 years ago, no direct spectroscopic evidence of these Andreev bound states exists to date. We propose a novel type of spectroscopy based on embedding a superconducting constriction, formed by a single-level molecule junction, in a microwave QED cavity environment. In the electron-dressed cavity spectrum we find a polariton excitation at twice the Andreev bound state energy, and a superconducting-phase-dependent ac Stark shift of the cavity frequency. Dispersive measurement of this frequency shift can be used for Andreev bound state spectroscopy.
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