Nonclassical Photon-Assisted Transport in Superconducting Tunnel Junctions

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.