  The effect of a black hole state evolution on the Hawking radiation is
studied using the final state boundary condition. It is found that
theormodynamic or statistical mechanical properties of a black hole depend
strongly on the unitary evolution operator $S$ which determines the black hole
state evolution. When the operator $S~$ is random unitary or psudeo random
unitary, a black hole emits thermal radiation as predicted by Hawking three
decades ago. On the other hand, it is found that the emission of Hawking
radiation could be suppressed when the evolution of a black hole state is given
by the generaor of the coherent state.
