Expanding the Black Hole Interior: Partially Entangled Thermal States in SYK

TL;DR

This paper introduces a new class of partially entangled thermal states in the SYK model, revealing their holographic duals as two black holes connected by a domain wall, and explores their interior structure and entanglement properties.

Contribution

It constructs and analyzes partially entangled states in SYK, linking them to novel black hole geometries with domain walls, and studies their interior and entanglement features.

Findings

Interior size varies with operator scale and temperature.

States interpolate between thermofield double and pure states.

Bulk reconstruction can access black hole interiors.

Abstract

We introduce a family of partially entangled thermal states in the SYK model that interpolates between the thermo-field double state and a pure (product) state. The states are prepared by a euclidean path integral describing the evolution over two euclidean time segments separated by a local scaling operator $\mathcal{O}$. We argue that the holographic dual of this class of states consists of two black holes with their interior regions connected via a domain wall, described by the worldline of a massive particle. We compute the size of the interior region and the entanglement entropy as a function of the scale dimension of $\mathcal{O}$ and the temperature of each black hole. We argue that the one-sided bulk reconstruction can access the interior region of the black hole.