Josephson Photonics with Simultaneous Resonances

TL;DR

This paper extends the theoretical understanding of Josephson photonics by analyzing systems with multiple simultaneous resonances, revealing how such conditions can induce mode coupling and generate entanglement.

Contribution

It generalizes previous models to include multiple resonant photon generation processes and explores their effects, notably mode coupling and entanglement creation.

Findings

Multiple resonances lead to effective mode coupling.

Simultaneous resonances can generate entanglement between modes.

Theoretical framework for complex Josephson photonics systems.

Abstract

Inelastic Cooper pair tunneling across a voltage-biased Josephson junction in series with one or more microwave cavities can generate photons via resonant processes in which the energy lost by the Cooper pair matches that of the photon(s) produced. We generalise previous theoretical treatments of such systems to analyse cases where two or more different photon generation processes are resonant simultaneously. We also explore in detail a specific case where generation of a single photon in one cavity mode is simultaneously resonant with the generation of two photons in a second mode. We find that the coexistence of the two resonances leads to effective couplings between the modes which in turn generate entanglement.