  Light incident upon molecules trigger fundamental processes in diverse
systems present in nature. However, under natural conditions, such as sunlight
illumination, it is impossible to assign known times for photon arrival owing
to continuous pumping, and therefore, the photo-induced processes cannot be
easily investigated. In this work, we theoretically demonstrate that
characteristics of sunlight photons such as photon number statistics and
spectral distribution can be emulated through quantum entangled photon pair
generated with the parametric down-conversion (PDC). We show that the average
photon number of the sunlight in a specific frequency spectrum, e.g., the
visible light, can be reconstructed by adjusting the PDC crystal length and
pump frequency, and thereby molecular dynamics induced by the pseudo-sunlight
can be investigated. The entanglement time, which is the hallmark of quantum
entangled photons, can serve as a control knob to resolve the photon arrival
times, enabling investigations on real-time dynamics triggered by the
pseudo-sunlight photons.
