Induced superconducting pairing in integer quantum Hall edge states

TL;DR

This paper demonstrates high-efficiency Andreev conversion in InAs quantum wells in the quantum Hall regime when coupled with NbTiN superconductors, highlighting strong hybridization and interface transparency.

Contribution

It provides experimental evidence of induced superconducting pairing in quantum Hall edge states and analyzes the process using a generalized Landauer-Büttiker formalism.

Findings

Negative downstream resistance observed

High Andreev conversion efficiency achieved

Strong hybridization of edge modes with superconductor states

Abstract

Indium Arsenide (InAs) near surface quantum wells (QWs) are promising for the fabrication of semiconductor-superconductor heterostructures given that they allow for a strong hybridization between the two-dimensional states in the quantum well and the ones in the superconductor. In this work we present results for InAs QWs in the quantum Hall regime placed in proximity of superconducting NbTiN. We observe a negative downstream resistance with a corresponding reduction of Hall (upstream) resistance, consistent with a very high Andreev conversion. We analyze the experimental data using the Landauer-B\"{u}ttiker formalism, generalized to allow for Andreev reflection processes. We attribute the high efficiency of Andreev conversion in our devices to the large transparency of the InAs/NbTiN interface and the consequent strong hybridization of the QH edge modes with the states in the superconductor.