  We propose a scheme by using the feed-forward control (FFC) to realize a
better effect of discrimination of two nonorthogonal states after passing a
noise channel based on the minimum- error (ME) discrimination. We show that the
application of our scheme can highly improve the effect of discrimination
compared with the ME discrimination without the FFC for any pair of
nonorthogonal states and any degree of amplitude damping (AD). Especially, the
effect of our optimal discrimination can reach that of the two initial
nonorthogonal pure states in the presence of the noise channel in a
deterministic way for equal a prior probabilities or even be better than that
in a probabilistically way for unequal a prior probabilities.
