Optimal1→Muniversal quantum cloning via spin networks

Abstract

We present a scheme which transforms a one-input qubit to M identical copies with optimal fidelity via free dynamical evolution of spin star networks. We demonstrate that the Heisenberg XXZ coupling can meet the challenge. The initial state of the copying machine and the parameters of the spin Hamiltonian are discussed in detail. Furthermore we have proposed a feasible method to prepare the initial state of the copying machine.