Nonequilibrium spectral diffusion due to laser heating in stimulated photon echo spectroscopy of low temperature glasses

TL;DR

This paper develops a quantitative theory to account for heating artifacts in three-pulse photon echo experiments on low temperature glasses, explaining observed spectral diffusion features without major modifications to existing models.

Contribution

It introduces a model that incorporates laser heating effects into spectral diffusion analysis, aligning experimental observations with standard tunneling models.

Findings

The theory accurately fits experimental data showing plateaus and bumps.

Heating artifacts significantly influence spectral linewidth measurements.

The model explains features without requiring a gap in flip rate distributions.

Abstract

A quantitative theory is developed, which accounts for heating artifacts in three-pulse photon echo (3PE) experiments. The heat diffusion equation is solved and the average value of the temperature in the focal volume of the laser is determined as a function of the 3PE waiting time. This temperature is used in the framework of nonequilibrium spectral diffusion theory to calculate the effective homogeneous linewidth of an ensemble of probe molecules embedded in an amorphous host. The theory fits recently observed plateaus and bumps without introducing a gap in the distribution function of flip rates of the two-level systems or any other major modification of the standard tunneling model.