Enhancement of femtosecond photon echo signals from an inhomogeneously broadened InAs quantum dot ensemble using chirped pulses

TL;DR

This paper demonstrates that using chirped pulses for adiabatic rapid passage significantly enhances photon echo signals in InAs quantum dot ensembles, enabling broadband and efficient optical quantum memory at telecom wavelengths.

Contribution

The study introduces a novel application of adiabatic rapid passage with chirped pulses to boost photon echo efficiency in inhomogeneously broadened quantum dot ensembles, validated by experiments and simulations.

Findings

Achieved a 3.2-fold increase in photon echo efficiency.

Demonstrated broadband rephasing across THz-scale inhomogeneous broadening.

Validated the physical model with numerical simulations.

Abstract

Photon echo (PE) techniques offer a promising approach to optical quantum memory, yet their implementation in conventional platforms, such as rare-earth-ion-doped crystals, is hindered by limited bandwidths. Semiconductor quantum dot (QD) ensembles, featuring THz-scale inhomogeneous broadening and sub-picosecond dynamics, provide an attractive alternative for ultrafast applications. However, achieving coherent control across such broad spectral ranges remains challenging due to detuning and spatial field inhomogeneities, which reduce PE efficiency. In this work, we experimentally demonstrated adiabatic rapid passage (ARP)-enhanced PE in dense, self-assembled InAs QD ensembles exhibiting THz-scale inhomogeneous broadening and operating at telecom wavelengths, achieving a 3.2-fold increase in echo efficiency. Chirped control pulses designed to satisfy adiabatic conditions across the ensemble enable broadband rephasing. Numerical simulations based on a two-level model reproduce the key experimental observations, including the ARP-induced enhancement, thereby validating the underlying physical picture. These results establish ARP as a robust and scalable approach for coherent control in InAs QD ensembles, with potential applications for ultrafast and broadband optical communication in the THz spectral region.