Macroscopic Coherent Rectification in Andreev Interferometers

TL;DR

This paper demonstrates that superconducting contacts in Andreev interferometers induce a large, controllable rectification effect that breaks Onsager reciprocity at finite bias, with potential for macroscopic applications.

Contribution

It reveals how superconductivity in specific geometries causes significant, tunable rectification effects in quantum coherent conductors, breaking traditional symmetry relations.

Findings

Rectification effect exceeds 5% of linear current at sub-gap biases.

Magnetic flux controls the direction and magnitude of rectification.

Breakdown of Onsager reciprocity at finite bias in these systems.

Abstract

We investigate nonlinear transport through quantum coherent metallic conductors contacted to superconducting components. We find that in certain geometries, the presence of superconductivity generates a large, finite-average rectification effect. Specializing to Andreev interferometers, we show that the direction and magnitude of rectification can be controlled by a magnetic flux tuning the superconducting phase difference at two contacts. In particular, this results in the breakdown of an Onsager reciprocity relation at finite bias. The rectification current is macroscopic in that it scales with the linear conductance, and we find that it exceeds 5% of the linear current at sub-gap biases of few tens of \mu eV's.