Ultrafast Mapping of Coherent Dynamics and Density Matrix Reconstruction in Terahertz-Assisted Laser Field

TL;DR

This paper introduces a rapid spectroscopic method using terahertz-assisted photoionization to reconstruct transient density matrices, enabling sub-femtosecond resolution of quantum coherence dynamics.

Contribution

It presents a novel protocol for mapping population and coherence elements onto spectrally separated peaks, allowing direct phase measurement and temporal resolution beyond pulse durations.

Findings

Effective mapping of density matrix elements onto spectral peaks

Temporal resolution of coherence beatings beyond pulse duration

Potential for sub-femtosecond measurements with laser sources

Abstract

A time-resolved spectroscopic protocol exploiting terahertz-assisted photoionization is proposed to reconstruct transient density matrix. Population and coherence elements are effectively mapped onto spectrally separated peaks in photoionization spectra. The beatings of coherence dynamics can be temporally resolved beyond the pulse duration, and the relative phase between involved states is directly readable from the oscillatory spectral distribution. As demonstrated by a photo-excited multilevel open quantum system, the method shows potential applications for sub-femtosecond time-resolved measurements of coherent dynamics with free electron lasers and tabletop laser fields.