TITLE: Implications of No-Hiding Theorem
QUESTION [3 upvotes]: I stumbled upon the following paper: https://inspirehep.net/record/712299 and the result derived therein, the No-Hiding theorem:

Consider now an arbitrary quantum state (mixed or potentially
  entangled to some external reference state) which is encoded
  into a larger Hilbert space through some unitary process.
  Suppose this encoding process completely hides the information
  about that state from a particular subsystem of that
  Hilbert space (i.e., the state of that subsystem shows no dependence
  on the state being being hidden). We prove that
  the hidden information is wholly encoded in the remainder
  of Hilbert space with no information stored in the correlations
  between the two subsystems [5]. Put differently, we prove
  that, unlike classical information, quantum mechanics allows
  only one way to completely hide an arbitrary quantum state
  from one of its subsystems: by moving it to its other subsystems.
  More importantly, we prove that this result is robust
  to imperfections in the hiding process.

This theorem seems to have implications for black hole evaporation, quantum teleportation and in general for thermodynamics:

the no-hiding theorem applies
  to any process hiding a quantum state, whether by erasure,
  randomization, thermalization or any other procedure.

More generally, it's a statement about the explicit conservation of quantum information. I'm surprised by the relatively low number of citations, considering the relevance of the theorem. Am I missing something? Have been the theorem disproved or weakened somehow by later results? If not, are there other implications of this theorem?

REPLY [0 votes]: In my understanding the theorem and its experimental verification show that quantum information can not be destroyed. This is not the same as saying it is conserved. It does not seem to establish that quantum information can not be created. One might appeal to a t-symmetry argument to extend it that way, but I am uncomfortable with the t-reversed experiment. Its interpretation is knotty.
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