Communications Physics (Jul 2023)

Intermediate states in Andreev bound state fusion

  • Christian Jünger,
  • Sebastian Lehmann,
  • Kimberly A. Dick,
  • Claes Thelander,
  • Christian Schönenberger,
  • Andreas Baumgartner

DOI
https://doi.org/10.1038/s42005-023-01273-2
Journal volume & issue
Vol. 6, no. 1
pp. 1 – 6

Abstract

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Abstract Hybridization is one of the most fundamental quantum mechanical phenomena, with the text book example of binding two hydrogen atoms in a hydrogen molecule. Here we report tunnel spectroscopy experiments illustrating the hybridization of another type of discrete quantum states, namely of superconducting subgap states that form in segments of a semiconducting nanowire in contact with superconducting reservoirs. We discuss a collection of intermediate states with unique (tunnel) spectroscopic fingerprints in the process of merging well-known individual bound states, hybridized by a central quantum dot and eventually coherently linking the reservoirs, carrying a Josephson current. These coupled and fused Andreev bound states can be seen as superconducting analogues to atomic and molecular single electron states in nature, and explain a variety of recent bound state spectra, with specific fingerprints that will have to be winnowed in future Majorana fusion experiments.