  We propose a novel means to isolate and quantify the effects of Berry force
on molecular dynamics using two reasonably strong continuous wave (CW) laser
fields with frequencies $\omega$ and $2\omega$. For molecules or materials with
three frequency-matching bright transitions
($|{0}\rangle\rightarrow|{1}\rangle$, $|{1}\rangle\rightarrow|{2}\rangle$,
$|{0}\rangle\rightarrow|{2}\rangle$) at frequencies ($\omega$, $\omega$,
$2\omega$) respectively, the effects of Berry curvature can be isolated by
varying the phase between the two laser fields ($\Delta \phi$) and monitoring
the dynamics. Moreover, we find that the resulting chemical dynamics can depend
critically on the sign of $\Delta \phi$; in other words, the effects of Berry
curvature can be enormous. Thus, this manuscript represents an unusual step
forward towards using light-matter interactions to affect chemical dynamics,
suggesting that topological concepts usually invoked in adiabatic quantum
optics and condensed matter can be directly applied to non-adiabatic chemical
excited state dynamics.

Chemical Physics