# Large Breakdowns of Entanglement Wedge Reconstruction

## TL;DR

This paper demonstrates that the region of a bulk spacetime reconstructable from boundary data can be significantly smaller than previously thought, especially near phase transitions or in high-energy states, challenging assumptions in holographic entanglement.

## Contribution

It reveals large separations between the reconstruction and entanglement wedges, highlighting limitations of current reconstruction methods in certain states and geometries.

## Key findings

- Reconstruction wedge can be much smaller than entanglement wedge.
- Large separations occur near phase transitions and in high-energy states.
- Quantum extremal surfaces can differ significantly from Ryu-Takayanagi surfaces.

## Abstract

We show that the bulk region reconstructable from a given boundary subregion --- which we term the reconstruction wedge --- can be much smaller than the entanglement wedge even when backreaction is small. We find arbitrarily large separations between the reconstruction and entanglement wedges in near-vacuum states for regions close to an entanglement phase transition, and for more general regions in states with large energy (but very low energy density). Our examples also illustrate situations for which the quantum extremal surface is macroscopically different from the Ryu-Takayanagi surface.