  Axial charge production at the early stage of heavy-ion collisions is
investigated within the framework of real-time lattice simulations at leading
order in QCD coupling. Starting from color glass condensate initial conditions,
the time evolution of quantum quark fields under classical color gauge fields
is computed on a lattice in longitudinally expanding geometry. We consider
simple color charge distributions in Lorentz contracted nuclei that realize
flux tube-like configurations of color fields carrying nonzero topological
charge after a collision. By employing the Wilson fermion extended to the
longitudinally expanding geometry, we demonstrate the realization of the axial
anomaly on the real-time lattice.
