Scrambling time from local perturbations of the eternal BTZ black hole

Understand

We compute the mutual information between finite intervals in two non-compact 2d CFTs in the thermofield double formulation after one of them has been locally perturbed by a primary operator at some time $t_\omega$ in the large $c$ limit.

• We determine the time scale, called the scrambling time, at which the mutual information vanishes and the original entanglement between the thermofield double gets destroyed by the perturbation.
• We provide a holographic description in terms of a free falling particle in the eternal BTZ black hole that exactly matches our CFT calculations.
• Our results hold for any time $t_\omega$.