Collapses and revivals of polarization and radiation intensity induced by strong exciton-vibron coupling

TL;DR

This paper investigates the complex quantum dynamics of strongly coupled exciton-vibron systems under external driving, revealing collapses and revivals in polarization and radiation spectra due to exciton-vibron interactions.

Contribution

It introduces a detailed analysis of transient exciton-vibron dynamics, highlighting the role of shifted Fock states as an effective reservoir and demonstrating collapse-revival phenomena.

Findings

Exciton polarization exhibits three distinct dynamical stages.

Shifted Fock states act as an effective reservoir influencing relaxation.

Radiation spectrum shows multiple spectral line splitting near exciton frequency.

Abstract

Recently, systems with strong coupling between electronic and vibrational degrees of freedom attract a great attention. In this work, we consider the transient dynamics of the system consisting of strongly coupled vibron and exciton driven by external monochromatic field. We show that under coherent pumping, polarization of exciton exhibits complex quantum dynamics which can be divided into three stages. At the first stage, exciton oscillations at its eigenfrequency relax due to the transition to set of shifted Fock states of vibrons. We demonstrate that these shifted Fock states play the role of an effective reservoir for the excited exciton state. The time of relaxation to this reservoir depends on exciton-vibron coupling. At the second stage, excitation, transferred to the reservoir of the vibronic shifted states at the first stage, returns into electronic degrees of freedom and revival of oscillations at exciton eigenfrequency appears. Thus, the dynamics of molecular polarization exhibit collapses and revivals. At the final stage, these collapses and revivals dissipate and polarization exhibits Rayleigh response at the frequency of the external field. Discovered collapses and revivals manifest in radiation spectrum as multiple splitting of the spectral line near the exciton transition frequency.