Demonstrating the decoupling regime of the electron-phonon interaction in a quantum dot using chirped optical excitation

TL;DR

This paper demonstrates a regime in quantum dot excitation where high chirp rate laser pulses cause decoupling of excitons from phonons at higher pulse areas, enabling effective rapid adiabatic passage despite phonon coupling.

Contribution

It introduces a novel high-chirp excitation regime that achieves exciton-phonon decoupling in quantum dots, enhancing control over quantum states.

Findings

Decoupling of excitons from phonons at high pulse areas

Reappearance of rapid adiabatic passage with chirped pulses

Good agreement between experimental results and theory

Abstract

Excitation of a semiconductor quantum dot with a chirped laser pulse allows excitons to be created by rapid adiabatic passage. In quantum dots this process can be greatly hindered by the coupling to phonons. Here we add a high chirp rate to ultra-short laser pulses and use these pulses to excite a single quantum dot. We demonstrate that we enter a regime where the exciton-phonon coupling is effective for small pulse areas, while for higher pulse areas a decoupling of the exciton from the phonons occurs. We thus discover a reappearance of rapid adiabatic passage, in analogy to the predicted reappearance of Rabi rotations at high pulse areas. The measured results are in good agreement with theoretical calculations.