Counting atypical black hole microstates from entanglement wedges

TL;DR

This paper demonstrates that a large number of atypical, disentangled black hole microstates with area law entanglement can account for almost all black hole entropy, challenging the typical volume law entanglement expectation.

Contribution

It shows the existence of sufficiently many disentangled microstates for black holes and constructs area law states in quantum many-body systems, providing new insights into black hole microstate structure.

Findings

Disentangled microstates can account for nearly all black hole entropy.

Existence of many area law states in microcanonical ensembles.

Explicit construction of area law and disentangled states.

Abstract

Disentangled black hole microstates are atypical states in holographic CFTs whose gravity duals do not have smooth horizons. If there exist sufficiently many disentangled microstates to account for the entire black hole entropy, then any black hole microstate can be written as a superposition of states without smooth horizons. We show that there exist sufficiently many disentangled microstates to account for almost the entire black hole entropy of a large AdS black hole at the semiclassical limit $G_N\rightarrow 0$. In addition, we also argue that in generic quantum many-body systems with short-ranged interactions, there exist sufficiently many area law states in the microcanonical subspace to account for almost the entire thermodynamic entropy in the standard thermodynamic limit. Area law states are atypical since a typical state should contain volume law entanglement. Furthermore, we also present an explicit way to construct such a set of area law states, and argue that the same construction may also be used to construct disentangled states.