  Photon antibunching, a hallmark of quantum light, has been observed in the
correlations of light from isolated atomic and atomic-like solid-state systems.
Two-dimensional semiconductor heterostructures offer a unique method to create
a quantum light source: a small lattice mismatch or relative twist in a
heterobilayer can create moir\'e trapping potentials for excitons which are
predicted to create arrays of quantum emitters. While signatures of moir\'e
trapped excitons have been observed, their quantum nature has yet to be
confirmed. Here we report photon antibunching from single moir\'e trapped
interlayer excitons in a heterobilayer. Via polarization resolved
magneto-optical spectroscopy, we demonstrate the discrete anharmonic spectra
arise from bound band-edge electron-hole pairs trapped in moir\'e potentials.
Finally, using an out-of-plane electric field, we exploit the large permanent
dipole of interlayer excitons to achieve large DC Stark tuning, up to 40 meV,
of the quantum emitters. Our results confirm the quantum nature of moir\'e
confined excitons and open opportunities to investigate their inhomogeneity and
interactions between the emitters or tune single emitters into resonance with
cavity modes or other emitters.
