  Unitarization of black hole evaporation requires that quantum information
escapes a black hole; an important question is to identify the mechanism or
channel by which it does so. Accurate counting of black hole states via the
Bekenstein-Hawking entropy would indicate this information should be encoded in
radiation with average energy flux matching Hawking's. Information can be
encoded with no change in net flux via fine-grained modulation of the Hawking
radiation. In an approximate effective field theory description, couplings to
the stress tensor of the black hole atmosphere that depend on the internal
state of the black hole are a promising alternative for inducing such
modulation. These can be picturesquely thought of as due to state-dependent
metric fluctuations in the vicinity of the horizon. Such couplings offer the
prospect of emitting information without extra energy flux, and can be shown to
do so at linear order in the couplings, with motivation given for possible
extension of this result to higher orders. The potential advantages of such
couplings to the stress tensor thus extend beyond their universality, which is
helpful in addressing constraints from black hole mining.

High Energy Physics - Theory;General Relativity and Quantum Cosmology