Few-cycle excitation of atomic coherence: an analytical solution beyond the rotating-wave approximation

Developing an analytical theory for atomic coherence driven by ultrashort laser pulses has proved to be challenging due to the breakdown of the rotating wave approximation (RWA). In this paper, we present an approximate analytical solution that describes a two-level atom under the excitation of a fa...

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Bibliographic Details
Published in:Journal of physics communications 2022-07, Vol.6 (7), p.75005
Main Authors: Pyvovar, Nazar, Zeng, Bing, Duan, Lingze
Format: Article
Language:English
Subjects:
analytical solution
few-cycle pulses
quantum coherence
rotating wave approximation
Schrödinger equation
two-level system
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Summary:Developing an analytical theory for atomic coherence driven by ultrashort laser pulses has proved to be challenging due to the breakdown of the rotating wave approximation (RWA). In this paper, we present an approximate analytical solution 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, a closed-form solution for Gaussian pulses is explicitly given, and the result is used to analyse the impact of carrier envelope phase on atomic population ratios. 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. The work lays out feasible theoretical paths toward analytically describing two-level atoms driven by ultrashort pulses.
ISSN:2399-6528
2399-6528
DOI:10.1088/2399-6528/ac7eaf