Fundamental strings, gravity and quantum processors

I will show that the Nambu-Goto equations for a string follow
from the junction conditions of three dimensional gravity. The solutions
of the junction conditions between two copies of an Einstein spacetime M
are in one-to-one correspondence with the solutions of the non-linear
Nambu-Goto equations obeyed by the average embedding of the junction in M
up to rigid parameters related to spacetime and worldsheet isometries. In
AdS, the solution of the Nambu-Goto equation corresponding to the bulk
junction can be decoded from the relative time reparametrization at the
dual CFT interface. In the more general constructions, each solution of
the Nambu-Goto equation should be understood as a quantum processor i.e. a
map between the Hilbert spaces of the CFT on the two sides of the dual
interface. These results, remarkably, can be generalized to multi-way
junctions between three dimensional spacetimes.