  Topological order (long-range entanglement) play important role in modern
condensed matter physics. In this paper, we will show that the four dimensional
black hole can also have topological order, by showing that the topological
entanglement entropy is non-zero. The properties of the topological order show
that the large diffeomorphisms will act as symmetry (not gauge) transformation
on the physical states. More importantly, the long-range entanglement will make
the Hawking radiation pure.
