Black hole microstates vs. the additivity conjectures

TL;DR

The paper discusses whether black hole microstates can be disentangled and account for entropy or if quantum information theory's additivity conjectures are violated, impacting understanding of black hole microphysics and quantum communication.

Contribution

It presents a dichotomy between potential violations of additivity conjectures or the existence of special microstates explaining black hole entropy.

Findings

Either extensive violations of additivity exist or

Disentangled microstates can account for Bekenstein-Hawking entropy

Implications for quantum information theory and black hole microphysics

Abstract

We argue that one of the following statements must be true: (a) extensive violations of quantum information theory's additivity conjectures exist or (b) there exists a set of `disentangled' black hole microstates that can account for the entire Bekenstein-Hawking entropy, up to at most a subleading $O(1)$ correction. Possibility (a) would be a significant result in quantum communication theory, demonstrating that entanglement can enhance the ability to transmit information much more than has currently been established. Option (b) would provide new insight into the microphysics of black holes. In particular, the disentangled microstates would have to have nontrivial structure at or outside the black hole horizon, assuming the validity of the quantum extremal surface prescription for calculating entanglement entropy in AdS/CFT.