2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93734I introduce rate-distortion theory for quantum coding, and derive a lower bound, involving the coherent information, on the rate at which qubits must be used to encode a quantum source with a given maximum level of distortion per source emission. The convexity of the "information rate-distortion function" which defines this bound is also derived.LaTeX, 6 pages, preliminary versionQuantum Physicstext