Microwave controlled phase coherent transport in mesoscopic S-N-S structures

TL;DR

This paper demonstrates that microwave fields significantly enhance subgap current in mesoscopic S-N-S structures through quantum interference, enabling weak electromagnetic signal detection and revealing effects of dephasing and relaxation.

Contribution

It introduces a novel microwave-controlled quantum interference mechanism in S-N-S structures that amplifies subgap current and can be used for sensitive electromagnetic detection.

Findings

Microwave fields increase subgap current by orders of magnitude.

Quantum interference causes oscillations in the I-V characteristics.

Potential application in detecting weak electromagnetic signals.

Abstract

We show that transport through a superconducting quantum point contact biased at subgap voltages is strongly affected by a microwave field. The subgap current is increased by several orders of magnitude. Quantum interference among resonant scattering events involving photon absorption is reflected as an oscillating structure in the I-V curve. We also discuss how the same interference effect can be applied for detecting weak electromagnetic signals up to the gap frequency, and how it is affected by dephasing and relaxation.