Black hole state evolution and Hawking radiation

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.