Realization of optimal symmetric universal and phase-covariant quantum cloning with quantum dot spins in cavity QED

Abstract

We present a scheme to implement a special quantum cloning machine with quantum dot spins in cavity QED. The quantum cloning machine copies the information from a photon to other two distant quantum dots trapped in cavities with the help of a single-photon pulse. Choosing the different parameters, the scheme can implement optimal symmetric 1 → 2 universal, optimal symmetric 1 → 2 phase-covariant and optimal symmetric economical 1 → 3 phase-covariant quantum cloning machines. The present scheme is more economical in saving resource compared with previous schemes.