Microscopic measurement of photon echo formation in groups of individual excitonic transitions

TL;DR

This paper investigates how photon echoes form in groups of localized excitonic transitions by measuring the third-order polarization, revealing the transition from free decay to rephasing and echo formation.

Contribution

It provides the first microscopic measurement of photon echo formation in individual excitonic groups, elucidating the rephasing mechanism at the transition level.

Findings

Photon echo arises from mutual rephasing of individual excitonic emissions.

The nonlinear response evolves from free decay to photon echo with increasing transition groups.

The study demonstrates the microscopic origin of photon echo in localized excitonic systems.

Abstract

The third-order polarization emitted from groups of individual localized excitonic transitions after pulsed optical excitation is measured. We observe the evolution of the nonlinear response from the case of a free polarization decay for a single transition, to that of a photon echo for many transitions. The echo is shown to arise from the mutual rephasing of the emission from individual transitions.