Quantum beats in the polarization response of a dielectric to intense few-cycle laser pulses

TL;DR

This paper explores how intense few-cycle laser pulses induce quantum beats in the polarization response of dielectrics, highlighting the role of charge carrier dynamics and phase sensitivity in nonlinear optical phenomena.

Contribution

It provides new insights into the polarization response mechanisms involving quantum beats and carrier dynamics under intense laser fields in dielectrics.

Findings

Quantum beats arise from superposition of conduction and valence band states.

Carrier dynamics significantly influence the polarization response.

Nonlinear polarization becomes phase-sensitive with Bloch oscillations or tunneling.

Abstract

We have investigated the polarization response of a dielectric to intense few-cycle laser pulses with a focus on interband tunnelling. Once charge carriers are created in an initially empty conduction band, they make a significant contribution to the polarization response. In particular, the coherent superposition of conduction- and valence-band states results in quantum beats. This quantum-beat part of the polarization response is affected by the excitation dynamics and attosecond-scale motion of charge carriers in an intense laser field. Our analysis shows that, with the onset of Bloch oscillations or tunnelling, the nonlinear polarization response becomes sensitive to the carrier-envelope phase of the laser pulse.