中国物理B ›› 2025, Vol. 34 ›› Issue (11): 113201-113201.doi: 10.1088/1674-1056/ae07c0

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A time-dependent generalized Floquet calculation of the laser-induced lineshape in attosecond transient absorption spectra

Xu-Han Wang(王旭涵), Di Zhao(赵迪)†, and Peng-Bo Li(李蓬勃)   

  1. Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
  • 收稿日期:2025-07-22 修回日期:2025-09-02 接受日期:2025-09-17 发布日期:2025-11-06
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. W2411002 and 12375018).

A time-dependent generalized Floquet calculation of the laser-induced lineshape in attosecond transient absorption spectra

Xu-Han Wang(王旭涵), Di Zhao(赵迪)†, and Peng-Bo Li(李蓬勃)   

  1. Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
  • Received:2025-07-22 Revised:2025-09-02 Accepted:2025-09-17 Published:2025-11-06
  • Contact: Di Zhao E-mail:d.zhao@mail.xjtu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. W2411002 and 12375018).

摘要: We introduce a time-dependent generalized Floquet (TDGF) approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet (XUV) pulse and a delayed few-cycle infrared (IR) laser pulse. This TDGF approach provides a Floquet understanding of the laser-induced change of resonant absorption lineshape. It is analytically demonstrated that the phase shift of the time-dependent dipole moment that results in the lineshape changes consists of two components, the adiabatic laser-induced phase (LIP) due to the IR-induced Stark shifts of adiabatic Floquet states and the non-adiabatic phase correction due to the non-adiabatic IR-induced coupling between adiabatic Floquet states. Comparisons of the spectral lineshape calculated based on the TDGF approach with the results obtained with the LIP model [Phys. Rev. A 88 033409 (2013)] and the rotating-wave approximation (RWA) are presented for several typical cases, demonstrating that TDGF universally and accurately captures IR-induced lineshape changes. It is suggested that the LIP model works as long as the generalized adiabatic theorem [PRX Quantum 2 030302 (2021)] holds, and the RWA works when the higher-order IR-coupling effect in the formation of adiabatic Floquet states is neglectable.

关键词: attosecond transient absorption spectra, Floquet analysis, non-adiabatic phase correction

Abstract: We introduce a time-dependent generalized Floquet (TDGF) approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet (XUV) pulse and a delayed few-cycle infrared (IR) laser pulse. This TDGF approach provides a Floquet understanding of the laser-induced change of resonant absorption lineshape. It is analytically demonstrated that the phase shift of the time-dependent dipole moment that results in the lineshape changes consists of two components, the adiabatic laser-induced phase (LIP) due to the IR-induced Stark shifts of adiabatic Floquet states and the non-adiabatic phase correction due to the non-adiabatic IR-induced coupling between adiabatic Floquet states. Comparisons of the spectral lineshape calculated based on the TDGF approach with the results obtained with the LIP model [Phys. Rev. A 88 033409 (2013)] and the rotating-wave approximation (RWA) are presented for several typical cases, demonstrating that TDGF universally and accurately captures IR-induced lineshape changes. It is suggested that the LIP model works as long as the generalized adiabatic theorem [PRX Quantum 2 030302 (2021)] holds, and the RWA works when the higher-order IR-coupling effect in the formation of adiabatic Floquet states is neglectable.

Key words: attosecond transient absorption spectra, Floquet analysis, non-adiabatic phase correction

中图分类号:  (Line shapes, widths, and shifts)

  • 32.70.Jz
42.50.Hz (Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift)