A Protocol for Spectroscopists to Isolate The Effect of Berry Geometric Magnetic Forces on Molecular Dynamics

TL;DR

This paper introduces a laser-based protocol to isolate and measure Berry curvature effects on molecular dynamics, enabling the study of topological influences in chemical processes through phase-controlled light-matter interactions.

Contribution

The authors propose a new experimental method using phase-controlled laser fields to isolate Berry force effects in molecular dynamics, bridging topological concepts with chemical dynamics.

Findings

Berry curvature effects can be isolated by phase variation of laser fields.

Chemical dynamics depend critically on the phase sign, indicating large Berry effects.

The approach links topological physics with non-adiabatic chemical processes.

Abstract

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.