Dynamic vibronic coupling in InGaAs quantum dots

TL;DR

This paper investigates how intense optical pulses can dynamically enhance electron-phonon interactions in InGaAs quantum dots, enabling rapid control of exciton states through phonon-assisted processes.

Contribution

It demonstrates the incoherent nature of phonon-assisted pumping and explores temperature effects, showing rapid exciton creation and destruction within 20 ps.

Findings

Dynamic vibronic coupling can be enhanced with intense optical pulses.

Phonon-assisted processes are incoherent and temperature-dependent.

Exciton states can be manipulated within ~20 ps.

Abstract

The electron-phonon coupling in self-assembled InGaAs quantum dots is relatively weak at low light intensities, which means that the zero-phonon line in emission is strong compared to the phonon sideband. However, the coupling to acoustic phonons can be dynamically enhanced in the presence of an intense optical pulse tuned within the phonon sideband. Recent experiments have shown that this dynamic vibronic coupling can enable population inversion to be achieved when pumping with a blue-shifted laser and for rapid de-excitation of an inverted state with red detuning. In this paper we confirm the incoherent nature of the phonon-assisted pumping process and explore the temperature dependence of the mechanism. We also show that a combination of blue- and red-shifted pulses can create and destroy an exciton within a timescale ~20 ps determined by the pulse duration and ultimately limited by the phonon thermalisation time.