LO Phonon-Induced Exciton Dephasing in Quantum Dots: An Exactly Solvable Model

TL;DR

This paper demonstrates that considering many excitonic states in quantum dots reveals LO phonon-induced spectral broadening and decoherence, challenging the previous belief that such states form everlasting polarons without broadening.

Contribution

The study introduces an exactly solvable model that extends previous limited-state models to many states, showing phonon-induced decoherence effects.

Findings

LO phonon coupling causes spectral broadening in multi-state models

Decoherence of optical response increases with more excitonic states

Contrasts with earlier models predicting no broadening in limited states

Abstract

It is widely believed that, due to its discrete nature, excitonic states in a quantum dot coupled to dispersionless LO phonons form everlasting mixed states (exciton polarons) showing no line broadening in the spectrum. This is indeed true if the model is restricted to a limited number of excitonic states in a quantum dot. We show, however, that extending the model to a large number of states results in LO phonon-induced spectral broadening and complete decoherence of the optical response.