  We study decoherence induced by a dynamic environment undergoing a quantum
phase transition. Environment's susceptibility to perturbations - and,
consequently, efficiency of decoherence - is amplified near a critical point.
Over and above this near-critical susceptibility increase, we show that
decoherence is dramatically enhanced by non-equilibrium critical dynamics of
the environment. We derive a simple expression relating decoherence to the
universal critical exponents exhibiting deep connections with the theory of
topological defect creation in non-equilibrium phase transitions.
