Atomistic Approach to Exciton-Phonon Couplings in Semiconductor Quantum Dots

TL;DR

This paper introduces an atomistic modeling approach for exciton-phonon interactions in semiconductor quantum dots, combining electronic structure calculations with open quantum system dynamics to improve understanding of their optical properties.

Contribution

It develops a nearly parameter-free, atomistic framework that accurately captures exciton-phonon couplings and predicts quantum dot emission characteristics beyond traditional analytical models.

Findings

Phonon spectral densities show deviations at higher energies due to realistic dot geometry.

Configuration mixing has a minor impact on exciton-phonon coupling.

Simulated radiative lifetimes match experimental measurements.

Abstract

We present a fully atomistic approach to exciton-phonon coupling in semiconductor quantum dots that bridges microscopic electronic-structure calculations with non-Markovian open-quantum-system dynamics. On the example of an InAsP quantum dot embedded in an InP matrix, we compute single-particle states using an ab initio-parametrized tight-binding model, then obtain correlated many-body wave functions of neutral excitons, biexcitons, and charged trions via the configuration-interaction method. Using these correlated states, we compute the exciton-phonon coupling matrix elements. The resulting phonon spectral densities for different excitonic complexes are compared with the widely used analytical super-Ohmic form and reveal deviations at higher energies originating from the realistic dot geometry and atomistic wave functions, whereas configuration mixing is found to play only a minor role. Furthermore, we extract radiative lifetimes comparable to values experimentally measured. As a direct application, we simulate the emission brightness of a pulsed-driven quantum dot and demonstrate that the atomistically derived spectral density substantially broadens the region of efficient off-resonant excitation compared to the analytical model. The presented framework provides a nearly parameter-free route to simulate the non-Markovian open quantum dynamics in semiconductor quantum dots.