Bounds on action of local quantum channels
نویسنده
چکیده
We derive an upper bound on the action of a direct product of two quantum maps (channels) acting on multi-partite quantum states. We assume that the individual channels Λj affect single-particle states so, that for an arbitrary input ρj , the distance Dj(Λj [ρj ], ρj) between the input ρj and the output Λj[ρj ] of the channel is less than ǫ. Given this assumption we show that for an arbitrary separable twopartite state ρ12 the distance between the input ρ12 and the output Λ1⊗Λ2[ρ12] fulfills the bound D12(Λ1 ⊗ Λ2[ρ12], ρ12) ≤ √
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