Efficient scheme to produce multi-particle entanglement with superconducting charge qubits

We propose an efficient scheme to implement high-fidelity multi-particle entangled states in the system consisting of superconducting charge qubits coupled through a single cavity mode. The manipulation is simply to apply specific gate voltages and external magnetic fields threaded through SQUIDs for fixed time. The total number of qubits which can be entangled is limited only from the decoherence time achieved in experiments. The gate operations are based on unconventional geometric phases and thus have built-in fault-tolerant features. The produced multi-qubit entangled states may have many applications.