  In collisions of ultra-relativistic nuclei, photon-tagged jets provide a
unique opportunity to compare jet production and modification due to parton
shower formation and propagation in strongly-interacting matter at vastly
different center-of-mass energies. We present first results for the cross
sections of jets tagged by an isolated photon to ${\cal O}(\alpha_{\rm em}
\alpha_s^2)$ in central Au+Au reactions with $\sqrt{s_{NN}}=200$ GeV at RHIC
and central Pb+Pb reactions with $\sqrt{s_{NN}}=2.76$ TeV at LHC. We evaluate
the increase in the transverse momentum imbalance of the observed $\gamma$+jet
state, induced by the dissipation of the parton shower energy due to strong
final-state interactions. Theoretical predictions to help interpret recent and
upcoming experimental data are presented.
