  We compute the spin-orbit correlations of quarks and gluons at small-$x$ and
show that the helicity and the orbital angular momentum of individual partons
are strongly anti-aligned even in unpolarized or spinless hadrons and nuclei.
Combined with the fact that gluons in the Color Glass Condensate are linearly
polarized, our finding indicates that the helicity and the orbital angular
momentum of single gluons are maximally entangled in a quantum mechanical
sense.
