Entanglement and teleportation of macroscopic continuous variables by superconducting devices

Abstract

A current-biased low-temperature superconducting Josephson junction (JJ) is dynamically describable by the quantized motion of a fictitious particle in a "washboard" potential. The long coherence time of tightly-bound states in the washboard potential of a JJ has prompted the effort to couple JJs and operate them as entangled qubits, capable of forming building blocks of a scalable quantum computer. Here we consider a hitherto unexplored quantum aspect of coupled JJs: the ability to produce Einstein-Podolsky-Rosen (EPR) entanglement of their continuous variables, namely, their magnetic fluxes and induced charges. Such entanglement, apart from its conceptual novelty, is the prerequisite for a far-reaching goal: teleportation of the flux and charge variables between JJs, implementing the transfer of an unknown quantum state along a network of such devices.