  Black hole (BH) evaporation is caused by creation of entangled
particle-antiparticle pairs near the event horizon, with one carrying positive
energy to infinity and the other carrying negative energy into the BH. Since
under the event horizon, particles always move toward the BH center, they can
only be absorbed but not emitted at the center. This breaks absorption-emission
symmetry and, as a result, annihilation of the particle at the BH center is
described by a non-Hermitian Hamiltonian. We show that due to entanglement
between photons moving inside and outside the event horizon, nonunitary
absorption of the negative energy photons near the BH center, alters the
outgoing radiation. As a result, radiation of the evaporating BH is not
thermal; it carries information about BH interior, and entropy is preserved
during evaporation.
