Quantum channel capacity
A quantum channel is a communication channel which can transmit quantum information, as opposed classical information. An example of quantum information is the direction of the spin of an electron. An example of classical information is the text of this article, which has been transmitted classically over your internet connection.
Although classical channels cannot transmit quantum information by themselves, they can be useful in combination with quantum channels. But the quantum channel will not be able to designate either classical information or quantum information, resulting in using either a classical channel or a quantum channel.