We derive that sufficient and necessary conditions for existence of a quantum channel φ and a generalized unitary operation E sendingof matrices, respectively. As an application, a sufficient and necessary condition for existence of a unitary duality quantum computer with given input-output states is obtained.
existence, quantum channel, generalized unitary operation, duality quantum computerCitation: Guo Z H, Cao H X. Existence and construction of a quantum channel with given inputs and outputs.