Comments on entanglement entropy

A new interpretation of entanglement entropy is proposed: entanglement entropy of a pure state with respect to a division of 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 the 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 the efficiency of quantum teleportation. Finally, the implications for the information loss problem and Hawking radiation are discussed.