Fano Interference at the Excitation of Coherent Phonons: Relation between the Asymmetry Parameter and the Initial Phase of Coherent Oscillations

TL;DR

This paper experimentally verifies the theoretical relationship between the Fano asymmetry parameter and the initial phase of coherent phonons, using ultrashort laser pulses in bismuth to demonstrate their interdependence.

Contribution

It provides experimental evidence linking the Fano asymmetry parameter with the initial phase of coherent phonons, confirming a theoretical prediction.

Findings

Negative asymmetry parameter correlates with increased initial phase.

As the modulus of the asymmetry parameter decreases, the initial phase increases.

The relationship is demonstrated in bismuth using ultrashort laser excitation.

Abstract

The theoretical assertion that the Fano asymmetry parameter and the asymptotic initial phase of a harmonic oscillator interacting with a continuum are interrelated is experimentally verified. By an example of coherent fully symmetric A1g phonons in bismuth that are excited by ultrashort laser pulses at liquid helium temperature, it is demonstrated that, for negative values of the asymmetry parameter, the asymptotic phase increases as the modulus of the parameter decreases.