Entanglement in Multipartite Josephson Systems

Superconducting devices have attracted significant interest both becausethese artificial macro-atoms allow us to investigate fundamentalproperties of quantum theory on a mesoscopic/macroscopic scale and morerecently in view of possible applications in quantum communication andinformation processing. So far, experimental research in this field hasmostly focused on the behaviour of a single isolated qubit while in thelast few years, significant achievements on superconducting two-qubitsystems were reported, i.e., the generation of entangled states insystems of coupled flux and phase qubits, as well as the observation ofquantum coherent oscillations and conditional gate operations using twocoupled superconducting charge qubits. Generation of multi-qubitentanglement will be the next significant and very challenging steptowards quantum information processing based on these scalablesolid-state systems. Within this framework the performances oftheoretical coupling schemes for the controlled generation andmanipulation of entangled states and of nonclassical superposition willbe discussed.