Improving the fidelity of quantum cloning by field-induced inhibition of the unwanted transition - art. no. 022315

The fidelity of quantum cloning is very often limited by the accompanying u nwanted transitions. We show how the fidelity can be improved by using a co herent cycling field to inhibit the unwanted transitions. We demonstrate th is explicitly in the context of the model of Simon et al. [J. Mod. Opt. 47, 233 (2000); Phys. Rev. Lett. 84, 2993 (2000)]. We also investigate the eff ects of the number of atoms on the quality of quantum cloning. We show the state dependence of the scheme, however all the input states of the qubit c an be cloned equally well by choosing the cycling field accordingly.