Andreev reflection in normal metal/charge-4e superconductor junctions

TL;DR

This paper explores Andreev reflection in normal metal/charge-4e superconductor junctions, revealing unique four-electron conversion processes and providing theoretical formulas for future experimental validation.

Contribution

It introduces a novel four-particle-type Landauer-Büttiker formula for charge-4e superconductors using nonequilibrium Green's functions, expanding understanding of their transport properties.

Findings

Behavior of Andreev coefficient with incident energy clarified

Conductance contributions from charge-4e Andreev reflection analyzed

Provides theoretical foundation for experimental detection of charge-4e superconductors

Abstract

We investigate the Andreev reflection in a normal metal/charge-4e superconductor junction.Compare with the electron-hole conversion in normal charge-2e superconductors, here four electrons participate simultaneously, enriching the possibility of conversion ways.Using nonequilibrium Green's function method, we obtain a four-particle-type Laudauer-B\"uttiker formula with generalized charge-4e anomalous Green's function to describe it.We then calculate and clarify the behavior of the Andreev coefficient with various incident energy and show the conductance contributed by it.Our research makes up the blank of research for transport property of charge-4e superconductors and can be served as hallmarks for future experimental verifications.