Beating signals in CdSe quantum dots measured by low-temperature 2D spectroscopy

TL;DR

This study uses low-temperature 2D spectroscopy to analyze quantum beat signals in CdSe quantum dots, revealing they originate from coherent LO-phonons without size dependence.

Contribution

It demonstrates that quantum beat signals in CdSe QDs are due to coherent LO-phonons, providing insight into quantum dynamics at low temperatures.

Findings

Beating signals originate from coherent LO-phonons.

No size dependence of LO-phonon frequency was observed.

Fourier analysis distinguishes positive and negative components.

Abstract

Advances in ultrafast spectroscopy can provide access to dynamics involving nontrivial quantum correlations and their evolutions. In coherent 2D spectroscopy, the oscillatory time dependence of a signal is a signature of such quantum dynamics. Here we study such beating signals in electronic coherent 2D spectroscopy of CdSe quantum dots (CdSe QDs) at 77 K. The beating signals are analyzed in terms of their positive and negative Fourier components. We conclude that the beatings originate from coherent LO-phonons of CdSe QDs. No evidence for the quantum dot size dependence of the LO-phonon frequency was identified.