  We show that the state of the Hawking radiation emitted from a large
Schwarzschild black hole (BH) deviates significantly from a classical state, in
spite of its apparent thermal nature. For this state, the occupation numbers of
single modes of massless asymptotic fields, such as photons, gravitons and
possibly neutrinos, are small and, as a result, their relative fluctuations are
large. The occupation numbers of massive fields are much smaller and suppressed
beyond even the expected Boltzmann suppression. It follows that this type of
thermal state cannot be viewed as classical or even semiclassical. We
substantiate this claim by showing that, in a state with low occupation
numbers, physical observables have large quantum fluctuations and, as such,
cannot be faithfully described by a mean-field or by a WKB-like semiclassical
state. Since the evolution of the BH is unitary, our results imply that the
state of the BH interior must also be non-classical when described in terms of
the asymptotic fields. We show that such a non-classical interior cannot be
described in terms of a semiclassical geometry, even though the average
curvature is sub-Planckian.

High Energy Physics - Theory;General Relativity and Quantum Cosmology