Ultrafast Quantum-path Interferometry Revealing the Generation Process of Coherent Phonons
arXiv:1905.08362 · doi:10.1103/PhysRevB.99.180301
Abstract
Optical dual-pulse pumping actively creates quantum-mechanical superposition of the electronic and phononic states in a bulk solid. We here made transient reflectivity measurements in an n-GaAs using a pair of relative-phase-locked femtosecond pulses and found characteristic interference fringes. This is a result of quantum-path interference peculiar to the dual-pulse excitation as indicated by theoretical calculation. Our observation reveals that the pathway of coherent phonon generation in the n-GaAs is impulsive stimulated Raman scattering at the displaced potential due to the surface-charge field, even though the photon energy lies in the opaque region.
6 + 4 pages, 5 + 3 figures