We propose an experimentally feasible scheme to implement the optimal general 1→2 phase-covariant quantum cloning machine based on cavity QED. In the scheme, the cavity is only virtually excited and thus the scheme is insensitive to the cavity field states and cavity decay.
We propose a scheme for implementing a partial general quantum cloning machine with superconducting quantum-interference devices coupled to a nonresonant cavity. By regulating the time parameters, our system can perform optimal symmetric (asymmetric) universal quantum cloning, optimal symmetric (asymmetric) phase-covariant cloning, and optimal symmetric economical phase-covariant cloning. In the scheme the cavity is only virtually excited, thus, the cavity decay is suppressed during the cloning operations.