  Ultracold polar molecules are promising for quantum information processing
and searches for physics beyond the Standard Model. Laser cooling to ultracold
temperatures is an established technique for trapped diatomic and triatomic
molecules. Further cooling of the molecules to near the motional ground state
is crucial for reducing various dephasings in quantum and precision
applications. In this work, we demonstrate Raman sideband cooling of CaF
molecules in optical tweezers to near their motional ground state, with average
motional occupation quantum numbers of $\bar{n}_{x}=0.16(12)$,
$\bar{n}_{y}=0.17(17)$ (radial directions), $\bar{n}_{z}=0.22(16)$ (axial
direction) and a 3-D motional ground state probability of $54\pm18\%$. This
paves the way to increase molecular coherence times in optical tweezers for
robust quantum computation and simulation applications.
