2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/90093We extend a low-rate improvement of the random coding bound on the reliability of a classical discrete memoryless channel to its quantum counterpart. The key observation that we make is that the problem of bounding below the error exponent for a quantum channel relying on the class of stabilizer codes is equivalent to the problem of deriving error exponents for a certain symmetric classical channel.9 pages, 1 figure. Changes in version 2: argument on the random coding bound expanded, minor errors correctedQuantum Physicstext