Strictly contractive quantum channels and physically realizable quantum computers
Strictly contractive quantum channels and physically realizable quantum computers
We study the robustness of quantum computers under the influence of errors modeled by strictly contractive channels. A channel T is defined to be strictly contractive if, for any pair of density operators \ensuremath{\rho}, \ensuremath{\sigma} in its domain, $\ensuremath{\Vert}T\ensuremath{\rho}\ensuremath{-}T\ensuremath{\sigma}{\ensuremath{\Vert}}_{1}<~k\ensuremath{\Vert}\ensuremath{\rho}\ensuremath{-}\ensuremath{\sigma}{\ensuremath{\Vert}}_{1}$ for some $0<~k<1$ (here $\ensuremath{\Vert}\ensuremath{\cdot}{\ensuremath{\Vert}}_{1}$ denotes the trace norm). In other …