Cite as: doi:10.26081/K6N917

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I will discuss recent work on a Hayden & Preskill like setup for both
maximally chaotic and sub- maximally chaotic quantum field theories. We
act on the vacuum with an operator in a Rindler like wedge R and
transfer a small subregion I of R to the other wedge. The chaotic
scrambling dynamics of the QFT Rindler time evolution reveals the
information in the other wedge. The holographic dual of this process
involves a particle excitation falling into the bulk and crossing into
the entanglement wedge of the complement to r = R\I. I will discuss
computations of various quantum information measures on the boundary
that tell us when the particle has entered this entanglement wedge. 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. The information quantities
that we will consider include the full vacuum modular energy R\I as well
as the fidelity between the state with the particle and the state
without. Along the way, I will discuss a new explicit formula for the
modular Hamiltonian of two intervals in an arbitrary 1+1 dimensional CFT
to leading order in the small cross ratio limit. I will also give an
explicit calculation of the Regge limit of the modular flowed chaos
correlator and find examples which do not saturate the modular chaos
bound. I will discuss 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. Finally, if
time allows, I will discuss upcoming work on the existence of quantum
extremal surfaces in the bulk dual of the SYK model which are associated
to a subset of SYK spins.
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