  Attosecond pulses can ionize atoms in a coherent process. Since the emerging
fragments are entangled, however, each preserves only a fraction of the initial
coherence, thus limiting the chance of guiding the ion subsequent evolution. In
this work, we use \emph{ab initio} simulations of pump-probe ionization of
helium above the $2s/2p$ threshold to demonstrate how this loss of coherence
can be controlled. Thanks to the participation of $2\ell n\ell'$ states,
coherence between the ionic $2s$ and $2p$ states, which are degenerate in the
non-relativistic limit, results in a stationary, delay-dependent electric
dipole. From the picosecond real-time beating of the dipole, caused by the
fine-structure splitting of the $n=2$ manifold, it is possible to reconstruct
all original ion coherences, including between antiparallel-spin states, which
are sensitive probe of relativistic effects in attosecond photoemission.
