Adiabatic rapid passage in quantum dots: phonon-assisted decoherence and biexciton generation

TL;DR

This paper investigates how phonon interactions affect the control of quantum dots using chirped laser pulses, revealing limitations in exciton occupation and biexciton generation, and compares simulation methods for modeling these effects.

Contribution

It provides a detailed analysis of phonon-assisted decoherence and biexciton formation in quantum dots under chirped laser excitation, and compares multiple simulation techniques.

Findings

Phonon interactions limit exciton occupation during adiabatic passage.

Biexciton generation occurs via phonon-assisted transitions.

Simulation methods agree at low temperatures.

Abstract

We study the evolution of a quantum dot controlled by a frequency-swept (chirped), linearly polarized laser pulse in the presence of carrier-phonon coupling. The final occupation of the exciton state is limited both due to phonon-induced transitions between the adiabatic spectral branches and because of phonon-assisted transitions to the biexciton state. When the biexciton shift is large enough, the quantum dot can be modeled as a two-level system, which corresponds to excitation with circularly polarized light. For this case, we compare different methods of simulations: (i) a time convolutionless method, (ii) correlation expansion and (iii) path integrals. We show that results obtained from these methods agree perfectly at low temperatures.