In heavy-ion collisions a new state of matter where quarks and gluons are deconfined, the quark-gluon plasma (QGP), is created. High-energy quarks and gluons are produced in the initial hard scattering and propagate through the QGP, which leaves its imprint in the internal structure of the reconstructed jets. Hence, the ability to measure detailed aspects of the substructure of heavy-ion jets has provided us with a new window into the QGP internal dynamics. In this talk, I present a new approach to jet substructure in heavy-ion collisions based on the study of correlation functions of energy flow operators (energy correlators). This approach is based on the insight that the dynamics of the QGP is imprinted at specific time scales in the jet, which will be reflected as changes in the shape of the correlator. We analyze the two-point correlator of an in-medium massless quark jet within different jet quenching formalisms, showing its sensitivity to the resolution scale of the QGP: the energy scale at which in-medium emissions start to be resolved by the QGP (color coherence).
