Quantum channel

A quantum channel is a communication channel that can transmit quantum information. One possibility is the transfer of information with or without quantum storage. An example of quantum information is the spin of a photon (mainly the polarization state ); making it possible, for example, an encrypted or tap-proof transmission of information ( quantum cryptography ).

A quantum channel is mathematically by a so-called super- operator ( i.e., an operator, who acts on operators) described with specific properties. This super- operator acts on the density operator describing the quantum state on the transmitter side, and thus indicates the transmission to the receiver side.