Bouncing inside the horizon and scrambling delays

TL;DR

This paper investigates how charge affects the scrambling time in charged AdS black holes, revealing that while the standard calculation suggests delays, the actual scrambling onset may not be longer, with bounce behavior playing a key role.

Contribution

It introduces a model of charged perturbations as bouncing shells inside black holes and challenges the conventional understanding of charge increasing scrambling time.

Findings

Adding charge increases the standard scrambling time estimate.

Bounce behavior suggests the actual scrambling onset may be delayed, not the total time.

A boundary four-point function detects the bounce inside the black hole.

Abstract

We study charged perturbations of the thermofield double state dual to a charged AdS black hole. We model the perturbation by a massless charged shell in the bulk. Unlike the neutral case, all such shells bounce at a definite radius, which can be behind the horizon. We show that the standard "shock wave" calculation of a scrambling time indicates that adding charge increases the scrambling time. We then give two arguments using the bounce that suggest that scrambling does not actually take longer when charge is added, but instead its onset is delayed. We also construct a boundary four point function which detects whether the shell bounces inside the black hole.