Optical realization of optimal symmetric universal and phase-covariant quantum cloning

We propose an experimentally unified linear optical scheme to implement the optimal symmetric one to two (1 -> 2) universal, optimal symmetric 1 -> 2 phase-covariant and optimal symmetric economical one to three (1 -> 3) phase-covariant quantum cloning machines of the polarization state of the single photon. This scheme requires single-photon sources as the input state. Here, we use a laser beam attenuated to the single-photon level as the input source. The scheme relies on one polarized qubit and two location qubits and it also involves linear optical elements. It is shown that under certain conditions, the scheme is feasible by current experimental technology.