The explicitly imported KSW conversion

For a finite-dimensional channel $\mathcal{N}$ and a complementary channel $\mathcal{E}$ from the same Stinespring isometry, set

The KSW information–disturbance theorem gives

We import this theorem from KSW, using Schrödinger-picture diamond norms, equivalently the Heisenberg-picture completely bounded norms of the adjoint maps.