2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/95058We address the problem of finding the optimal joint unitary transformation on system + ancilla which is the most efficient in programming any desired channel on the system by changing the state of the ancilla. We present a solution to the problem for dim(H)=2 for both system and ancilla.8 pages, ws-procs9x6 and qcircuit styles. Proceedings "26th Conference: QP and IDA" - Levico (Trento), February 20-26, 2005Quantum Physicstext