Thispapersolvesthenewlyconstructednonlinearmasterequationdρ/dt=κ[2f(N)aρ(1/f(N-1))a+-a+aρ-ρa+a],wheref(N)isanoperator-valuedfunctionofN=a+a,fordescribingamplitudedampingchannel,andderivestheinfiniteoperatorsumrepresentationofquasi-Krausoperatorsforthedensityoperator.Italsoshowsthatinthisnonlinearprocesstheinitialpurenumberstatedensityoperatorwillevolveintothebinomialfield(amixedstate)whenf(N)=1/(N+1)～(1/2).
