Infinite-dimensional Kraus operators for describing amplitude-damping channel and laser process

Based on the preceding Communication (Hong-yi Fan, Li-yun Hu, Opt. Commun. 281 (2008) 5571) we identify the explicit infinite-dimensional Kraus operators for describing amplitude-damping channel and for laser process, the normalization of Kraus operators are proved. The evolution of an initial pure coherent state into a mixed state in the laser process is clearly shown by virtue of the explicit operator-sum representation of the Kraus operator.