  Time-resolved Raman spectroscopy techniques offer various ways to study the
dynamics of molecular vibrations in liquids or gases and optical phonons in
crystals. While these techniques give access to the coherence time of the
vibrational modes, they are not able to reveal the fragile quantum correlations
that are spontaneously created between light and vibration during the Raman
interaction. Here, we present a scheme leveraging universal properties of
spontaneous Raman scattering to demonstrate Bell correlations between light and
a collective molecular vibration. We measure the decay of these hybrid
photon-phonon Bell correlations with sub-picosecond time resolution and find
that they survive over several hundred oscillations at ambient conditions. Our
method offers a universal approach to generate entanglement between light and
molecular vibrations. Moreover, our results pave the way for the study of
quantum correlations in more complex solid-state and molecular systems in their
natural state.
