Coherent Control over Liouville-Space Pathways Interference in Transient Four-Wave Mixing Spectroscopy

A novel interference effect in transient four-wave mixing is demonstrated. The phenomenon is based on phase-controlled Liouville-space pathways interference and observed in the heterodyne-detected stimulated photon echo. Changing the phase difference between the first two excitation pulses from $\pi /2\mathrm{}$ to 0 leads from no signal to maximum echo signal. A Brownian oscillator dynamical model is successfully used to analyze the effect and simulate the experimental data. The relation between this time-domain interference effect and dephasing-induced resonance in four-wave mixing spectroscopy is elaborated.