  A new interpretation of entanglement entropy is proposed: entanglement
entropy of a pure state with respect to a division of a Hilbert space into two
subspaces 1 and 2 is an amount of information, which can be transmitted through
1 and 2 from a system interacting with 1 to another system interacting with 2.
The transmission medium is quantum entanglement between 1 and 2. In order to
support the interpretation, suggestive arguments are given: variational
principles in entanglement thermodynamics and quantum teleportation. It is
shown that a quantum state having maximal entanglement entropy plays an
important role in quantum teleportation. Hence, the entanglement entropy is, in
some sense, an index of efficiency of quantum teleportation. Finally,
implications for the information loss problem and Hawking radiation are
discussed.
