  Fundamental entanglement related challenges have prevented quantum
interference-based control (i.e. coherent control) of collisional cross
sections from being implemented in the laboratory. Here, differential cross
sections for reactive scattering at low temperatures are shown to provide a
unique opportunity to display such interference-based control by forming
coherent superpositions of degenerate rotational states of reactant molecules
|jmi with different m. In particular, we identify and quantify a unique
signature of coherent control in reactive scattering with applications to F +
H2 ! H + HF and HF + D F + HD ! HD + F at 11 K. Control is shown to be
extensive.
