Dephasing of InAs quantum dot p-shell excitons using two-dimensional coherent spectroscopy

TL;DR

This study investigates the dephasing mechanisms of s-shell and p-shell excitons in InAs quantum dots using two-dimensional coherent spectroscopy, revealing temperature-dependent dephasing processes and the influence of phonon interactions.

Contribution

It provides new insights into exciton dephasing in quantum dots, highlighting the roles of lifetime, pure dephasing, and phonon coupling across different energy shells.

Findings

s-shell exciton dephasing is lifetime limited at low temperatures

p-shell excitons exhibit significant pure dephasing due to spin state scattering

phonon coupling significantly affects dephasing at higher temperatures

Abstract

The dephasing mechanisms of p-shell and s-shell excitons in an InAs self-assembled quantum dot ensemble are examined using two-dimensional coherent spectroscopy (2DCS). 2DCS provides a comprehensive picture of how the energy level structure of dots affects the exciton dephasing rates and recombination lifetimes. We find that at low temperatures, dephasing of s-shell excitons is lifetime limited, whereas p-shell excitons exhibit significant pure dephasing due to scattering between degenerate spin states. At elevated temperatures, quadratic exciton-phonon coupling plays an important role in both s-shell and p-shell exciton dephasing. We show that multiple p-shell states are also responsible for stronger phonon dephasing for these transitions