Photon echo transients from an inhomogeneous ensemble of semiconductor quantum dots

TL;DR

This paper investigates how inhomogeneity in quantum dot ensembles affects photon echo timing, revealing deviations from conventional sequences and complex echo behaviors depending on pulse areas.

Contribution

It demonstrates the impact of ensemble inhomogeneity on photon echo timing and provides detailed experimental and theoretical analysis of these effects.

Findings

Retarded echo observed for π/2 pulses

Advanced echo observed for 3π/2 pulses

Complex photon echo formation influenced by pulse area variation

Abstract

An ensemble of quantum dot excitons may be used for coherent information manipulation. Due to the ensemble inhomogeneity any optical information retrieval occurs in form of a photon echo. We show that the inhomogeneity can lead to a significant deviation from the conventional echo timing sequence. Variation of the area of the initial rotation pulse, which generates excitons in a dot sub-ensemble only, reveals this complex picture of photon echo formation. We observe a retarded echo for {\pi}/2 pulses, while for 3{\pi}/2 the echo is advanced in time as evidenced through monitoring the Rabi oscillations in the time-resolved photon echo amplitude from (In,Ga)As/GaAs self-assembled quantum dot structures and confirmed by detailed calculations.