Spin correlations in nonlinear optical response: Light-induced Kondo effect

TL;DR

This paper reveals how spin correlations induce a Kondo effect in nonlinear optical responses, showing a tunable Kondo temperature and unique spectral features in Fermi sea systems under optical excitation.

Contribution

It demonstrates the emergence of Kondo physics in nonlinear optics and introduces the concept of a light-induced Kondo temperature tunable by optical parameters.

Findings

Logarithmic divergence in third-order susceptibility at absorption threshold.

Tunable Kondo temperature via pump field intensity and frequency.

Narrow peak in pump-probe spectrum below linear absorption onset.

Abstract

We study the role of spin correlations in nonlinear absorption due to optical transitions from a deep impurity level to states above a Fermi sea. We demonstrate that the Hubbard repulsion between two electrons occupying the impurity state leads to a logarithmic divergence of the third-order nonlinear optical susceptibility at the absorption threshold. This divergence is a manifestation of the Kondo physics in the nonlinear optical response of Fermi sea systems. Remarkably, the light-induced Kondo temperature, which governs the shape of the Kondo-absorption spectrum, can be tuned by varying the intensity and frequency of the pump optical field. We also show that, for off-resonant pump excitation, the pump-probe spectrum exhibits a narrow peak below the linear absorption onset.