COUPLING SUPERCONDUCTING FLUX QUBITS USING AC MAGNETIC FLXUES

Exploiting the intrinsic nonlinearity of superconducting Josephson junctions, we propose a scalable circuit with superconducting (SC) qubits which is very similar to the successful one now being used for trapped ions. The SC qubits are coupled to the "vibrational" mode provided by a superconducting LC circuit or its equivalent (e.g., a SQUID). Both single-qubit rotations and qubit-LC-circuit couplings/decouplings can be controlled by varying frequencies of the applied ac magnetic fluxes. The circuit is scalable since the qubit-qubit interactions, mediated by the LC circuit, can be selectively performed, and the information transfer can be realized in a controllable way. We also discuss how to control the couplings between the qubit and the data bus via "dressed" qubit states. This approach can also be reduced to the one used for trapped ions.