It has recently been shown that the Nambu-Goto equation for a string emerges from the junction conditions in three-dimensional gravity. Holographically, gravitational junctions are dual to interfaces in conformal field theory. We demonstrate that each stringy mode of the junction corresponds to a universal $\mathcal{ H}_{ in}\rightarrow \mathcal{ H}_{ out}$ quantum map between in and out Hilbert spaces of excitations scattered at the interface, and also a universal $\mathcal{ H}_{ L}\rightarrow \mathcal{ H}_{ R}$ quantum map relating the excitations on both sides. These quantum maps generalize those realized by defect operators, preserve the conformal boundary condition at the interface, and realize a tunable energy transmitter.
Categories: hep-th cond-mat.str-el gr-qc