Transitions in the communication capacity of dissipative qubit channels.
The information transmission is studied for quantum channels in which the noise includes dissipative effects, more specifically, nonunitality. Noise is usually a nuisance but can sometimes be helpful. For these channels, the communication capacity is shown to increase with the dissipative component of the noise and may exhibit transitions beyond which it increases faster. The optimal states are constructed analytically as well as the pertaining "phase" diagram.
Daems
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QuIC, Ecole Polytechnique, Université Libre de Bruxelles, 1050 Brussels, Belgium. ddaems@ulb.ac.be