  We propose how to realize a three-step controlled-phase gate of one
superconducting qubit simultaneously controlling n qubits selected from N
qubits in a cavity (1<n<N). The operation time of this gate is independent of
the number n of qubits involved in the gate operation. This phase gate
controlling at once n qubits is insensitive to the initial state of the cavity
mode and can be used to produce an analogous CNOT gate simultaneously acting on
n qubits.
