  Coherent control of interfering one- and two-photon processes has for decades
been the subject of research to achieve the redirection of photocurrent. The
present study develops two-pathway coherent control of ground state helium atom
above-threshold photoionization for energies up to the $N=2$ threshold, based
on a multichannel quantum defect and R-matrix calculation. Three parameters are
controlled in our treatment: the optical interference phase $\Delta\Phi$, the
reduced electric field strength
$\chi=\mathcal{E}_{\omega}^2/{\mathcal{E}_{2\omega}}$, and the final state
energy $\epsilon$. A small energy change near a resonance is shown to flip the
emission direction of photoelectrons with high efficiency, through an example
where $90\%$ of photoelectrons whose energy is near the $2p^2\ ^1S^e$ resonance
flip their emission direction. However, the large fraction of photoelectrons
ionized at the intermediate state energy, which are not influenced by the
optical control, make this control scheme challenging to realize
experimentally.
