  Two-dimensional (2D) noble-metal dichalcogenides have emerged as a new
platform for the realization of versatile flat optics with a considerable
degree of miniaturization. However, light field manipulation at the atomic
scale is widely considered unattainable since the vanishing thickness and
intrinsic losses of 2D materials completely suppress both resonances and phase
accumulation effects. Empowered by conventionally perceived adverse effects of
intrinsic losses, we show that the structured PtSe2 films integrated with a
uniform substrate can regulate nontrivial singular phase and realize
atomic-thick meta-optics in the presence of topological darkness. We
experimentally demonstrate a series of atomic-thick binary meta-optics that
allows angle-robust and high unit-thickness diffraction efficiency of 0.96%/nm
in visible frequencies, given its thickness of merely 4.3 nm. Our results
unlock the potential of a new class of 2D flat optics for light field
manipulation at an atomic thickness.
