Fast generation of multiparticle entangled state for flux qubits in a circle array of transmission line resonators with tunable coupling

摘要

We study a one-step approach to the fast generation ofGreenberger-Horne-Zeilinger (GHZ) states in a circuit QED system withsuperconducting flux qubits. The GHZ state can be generated in about 10 ns,which is much shorter than the coherence time of flux qubits and comparablewith the time of single-qubit operation. In our proposal, a time-dependentmicrowave field is applied to a superconducting transmission line resonator(TLR) and displaces the resonator in a controlled manner, thus inducingindirect qubit-qubit coupling without residual entanglement between the qubitsand the resonator. The design of a tunably coupled TLR circle array provides uswith the potential for extending this one-step scheme to the case of manyqubits coupled via several TLRs.