Entanglement and teleportation of macroscopic continuous variables by superconducting devices

摘要

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