  Electron-phonon coupling plays a central role for time-dependent phenomena in
condensed matter, for example in photo-excitation experiments. We use the
continuous-time quantum Monte Carlo method to study the real-time evolution of
charge and spin correlation functions of a Peierls insulator after a quench to
a noninteracting Hamiltonian. This approach gives exact results, and fully
takes into account quantum phonon effects without relying on a Hilbert space
truncation. It is also free from a dynamical sign problem. The observed time
dependence is compared to free-fermion time evolution starting from a dimerized
state. Our exact results provide a benchmark for more realistic calculations,
and may be directly applicable to experiments with cold atoms or trapped ions.
