CAPACITIES OF QUANTUM ERASURE CHANNELS

The quantum analog of the classical erasure channel provides a simple example of a channel whose asymptotic capacity for faithful transmissi on of intact quantum states, with and without the assistance of a two- way classical side channel, can be computed exactly. We derive the qua ntum and classical capacities for the quantum erasure channel and rela ted channels, and compare them to the depolarizing channel, for which only upper and lower bounds on the capacities are known.