Andreev bound state spectroscopy of a quantum-dot-based Aharonov-Bohm interferometer with superconducting terminals

TL;DR

This paper analytically and numerically studies a superconducting quantum-dot Aharonov-Bohm interferometer, revealing its spectral equivalence to a simpler system and demonstrating how it exhibits Josephson diode effects through Andreev bound states.

Contribution

It establishes a spectral equivalence between a complex interferometer and a simpler quantum dot system, providing new insights into its behavior and Josephson diode effects.

Findings

Spectral equivalence to a simpler quantum dot system.

Conditions for doublet chimney formation in phase diagrams.

Identification of Josephson diode effect via Andreev bound states.

Abstract

We analytically and numerically investigate an Aharonov-Bohm interferometer with two superconducting terminals and a strongly correlated quantum dot in one arm. Through a rigorous derivation, we prove that this double-path interferometer is spectrally equivalent to a simpler system: an interacting quantum dot coupled to a non-interacting side-coupled proximitized mode and a semiconductor lead. This equivalence reveals a simple interpretation of the interferometer's behavior through the competition of a geometric factor $\chi$, a key parameter characterizing the anomalous part of the hybridization function, with the properties of the side-coupled mode. We identify the conditions for the formation of doublet chimney in the phase diagrams in more general setting. Moreover, we show how the obtained Andreev bound state spectra clearly indicate the presence of Josephson diode effect generated by interferometric phenomena.