We present an alternative approach to the derivation of benchmarks for
quantum channels, such as memory or teleportation channels. Using the concept
of effective entanglement and the verification thereof, a testing procedure is
derived which demands very few experimental resources. The procedure is
generalized by allowing for mixed test states. By constructing optimized
measure & re-prepare channels, the benchmarks are found to be very tight in the
considered experimental regimes.Comment: 11 Pages, 9 Figures, published versio