  Simulating complex many-body quantum phenomena is a major scientific impetus
behind the development of quantum computing, and a range of technologies are
being explored to address such systems. We present the results of the largest
photonics-based simulation to date, applied in the context of subatomic
physics. Using an all-optical quantum frequency processor, the ground-state
energies of light nuclei including the triton ($^3$H), $^{3}$He, and the alpha
particle ($^{4}$He) are computed. Complementing these calculations and
utilizing a 68-dimensional Hilbert space, our photonic simulator is used to
perform sub-nucleon calculations of the two-body and three-body forces between
heavy mesons in the Schwinger model. This work is a first step in simulating
subatomic many-body physics on quantum frequency processors---augmenting
classical computations that bridge scales from quarks to nuclei.
