  In a two sided black hole, systems falling in from opposite asymptotic
regions can meet inside the black hole and interact. This is the case even
while the two CFTs describing each asymptotic region are non-interacting. Here,
we relate these behind the horizon interactions to non-local quantum
computations. This gives a quantum circuit perspective on these interactions,
which applies whenever the interaction occurs in the past of a certain extremal
surface that sits inside the black hole and in arbitrary dimension. Whenever
our perspective applies, we obtain a boundary signature for these interior
collisions which is stated in terms of the mutual information. We further
revisit the connection discussed earlier between bulk interactions in one sided
AdS geometries and non-local computation, and recycle some of our techniques to
offer a new perspective on making that connection precise.
