Scattering Strings Off Quantum Extremal Surfaces

I will discuss recent work on a Hayden & Preskill like setup for both maximally chaotic and sub- maximally chaotic quantum field theories. I will discuss computations of various quantum information measures on the boundary that tell us when a particle has left the entanglement wedge of a given region. In a maximally chaotic theory, these measures indicate a sharp transition where the particle enters the wedge exactly when the insertion is null separated from the quantum extremal surface for r. For sub-maximally chaotic theories, we find a smoothed crossover at a delayed time given in terms of the smaller Lyapunov exponent and dependent on the time-smearing scale of the probe excitation. I will speculate on the extent to which our results reveal properties of the target of the probe excitation as a “stringy quantum extremal surface” or simply quantify the probe itself thus giving a new approach to studying the notion of longitudinal string spreading.