Intermediate states in Andreev bound state fusion

TL;DR

This paper investigates the hybridization process of superconducting subgap states in nanowires, revealing intermediate states during state merging, which could inform future Majorana fusion experiments and explain recent bound state observations.

Contribution

It provides experimental evidence and analysis of intermediate states in Andreev bound state fusion, advancing understanding of quantum state hybridization in superconducting nanowires.

Findings

Identification of intermediate states during bound state merging

Explanation of hybridization process in superconducting nanowires

Potential implications for Majorana fermion experiments

Abstract

Hybridization is a very fundamental quantum mechanical phenomenon, with the text book example of binding two hydrogen atoms in a hydrogen molecule. In semiconductor physics, a quantum dot (QD) can be considered as an artificial atom, with two coupled QDs forming a molecular state, and two electrons on a single QD the equivalent of a helium atom. 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 show and explain a collection of intermediate states found in the process of merging individual bound states, hybridizing with a central QD and eventually coherently linking the reservoirs. These results may serve as a guide in future Majorana fusion experiments and explain a large variety of recent bound state experiments.