Quantum cloning in spin networks
Gabriele De Chiara, Rosario Fazio, Chiara Macchiavello, Simone Montangero, G. Massimo Palma · Physical Review A · 2004
We introduce an approach to quantum cloning based on spin networks and we demonstrate that phase covariant cloning can be realized using no external control but only with a proper design of the Hamiltonian of the system. In the $1\ensuremath{\rightarrow}2$ cloning we find that the $XY$ model saturates the value for the fidelity of the optimal cloner and gives values comparable to it in the general $N\ensuremath{\rightarrow}M$ case. We finally discuss the effect of external noise. Our protocol is much more robust to decoherence than a conventional procedure based on quantum gates.