ar X iv : q ua nt - p h / 05 06 16 8 v 1 2 0 Ju n 20 05 Local vs Nonlocal cloning in a noisy environment
نویسنده
چکیده
We address the distribution of quantum information among many parties in the presence of noise. In particular, we consider how to optimally send to m receivers the information encoded into an unknown coherent state. On one hand, a local strategy is considered, consisting in a local cloning process followed by direct transmission. On the other hand, a telecloning protocol based on nonlocal quantum correlations is analyzed. Both the strategies are optimized to minimize the detrimental effects due to losses and thermal noise along the propagation. The comparison between the local and the nonlocal protocol shows that telecloning is more effective than local cloning for a wide range of noise parameters. Our results indicate that nonlocal strategies can be more robust against noise than local ones, thus being suitable candidates to play a major role in quantum information networks. PACS numbers: 03.67.Mn, 03.67.Hk Local vs Nonlocal cloning in a noisy environment 2
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