  A conceptually simple method for derivation of lower bounds on the error
exponent of specific families of block codes used on classical-quantum channels
with arbitrary signal states over a finite Hilbert space is presented. It is
shown that families of binary block codes with appropriately rescaled binomial
multiplicity enumerators used on binary classical-quantum channels and decoded
by the suboptimal decision rule introduced by Holevo attain the expurgated and
cutoff rate lower bounds on the error exponent.
