Simple scheme for generating an n-qubit W state in cavity QED

A simple scheme is proposed to generate an n-qubit W state in cavity QED. Conditioned on no photon leakage from the cavity, the n-qubit W state can be generated by resonant interaction between atoms and the cavity if the cavity is initially prepared in the single-photon state and all the atoms are in the ground states. We check the time evolution of the system involving decay, and show that, since the required interaction time is very short, with present cavity QED techniques, the success probability of our scheme is almost unity.