Generation of N-qubit W states with rf SQUID qubits by adiabatic passage

A simple scheme is presented to generate N-qubit W states with rf superconducting quantum interference devices (SQUIDs) in cavity QED through adiabatic passage. Because of the achievable strong coupling for rf SQUID qubits embedded in cavity QED, we can get the desired state with high success probability. Furthermore, the scheme is insensitive to the position inaccuracy of the rf SQUID. Numerical simulation shows that, by using present experimental techniques, we can achieve our scheme with very high success probability, and the fidelity could eventually be unity with the help of dissipation.