Few-cycle excitation of atomic coherence: A closed-form analytical solution beyond the rotating-wave approximation

TL;DR

This paper derives a closed-form analytical solution for atomic coherence driven by ultrashort, few-cycle laser pulses without relying on the rotating wave approximation, enhancing understanding of ultrafast atomic interactions.

Contribution

It provides the first approximate, closed-form solution to the Schrödinger equation for two-level atoms under arbitrary-shaped, far-off-resonance, few-cycle pulses without using RWA.

Findings

Analytical solution validated against numerical results.

Applicable to Gaussian pulse shapes.

Outlines a method for more accurate nonlinear modeling.

Abstract

Developing an analytical theory for atomic coherence driven by ultrashort laster pulses has proved to be challenging due to the breakdown of the rotating wave approximation (RWA). In this paper, we present an approximate, closed-form solution to the Schrodinger equation that describes a two-level atom under the excitation of a far-off-resonance, few-cycle pulse of arbitrary shape without invoking the RWA. As an example of its applicability, an analytical solution for Gaussian pulses is explicitly given. Comparisons with numerical solutions validate the accuracy our solution within the scope of the approximation. Finally, we outline an alternative approach that can lead to a more accurate solution by capturing the nonlinear behaviors of the system.