Coherent-control mechanisms of Penning and associative ionization in cold He*(2 3S)-He*(2 3S) reactive scattering

We explore coherent control of Penning and associative ionization in cold collisions of metastable He*(2 S-3) atoms via the quantum interference between different states of the He*(2) collision complex. By tuning the preparation coefficients of the initial atomic spin states, we can benefit from the quantum interference between molecular channels to maximize or minimize the cross sections for Penning and associative ionization. In particular, we find that we can enhance the ionization ratio by 30% in the cold regime. This work is significant for the coherent control of chemical reactions in the cold and ultracold regimes.