Nonclassical Photon-Assisted Transport in Superconducting Tunnel Junctions

TL;DR

This paper theoretically explores how superconducting tunnel junctions interacting with nonclassical microwave states can reveal quantum properties of the environment and extend classical photon-assisted transport phenomena into the quantum regime.

Contribution

It introduces a theoretical framework for analyzing supercurrent in Josephson junctions coupled to nonclassical electromagnetic fields, enabling quantum state reconstruction.

Findings

Supercurrent analysis allows complete quantum state reconstruction.

Generalization of photon-assisted tunneling to the quantum regime.

Prediction of novel quantum transport phenomena in superconducting junctions.

Abstract

Advances in circuit quantum electrodynamics have enabled the generation of arbitrary nonclassical microwave states and paved the way for addressing novel physics questions. Here, we present a theoretical study of the electrical current in a Josephson tunnel junction interacting with a nonclassical electromagnetic environment. This allows us to generalize classical transport phenomena like photon-assisted tunneling and Shapiro steps to the quantum regime. We predict that the analysis of the supercurrent in such a setup enables the complete reconstruction of quantum states of the electromagnetic environment, something that is not possible with normal tunnel junctions.