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Envelope-induced asymmetry of the Autler-Townes doublet

Ayoub Ait Elarabi and András Csehi*

  • Department of Theoretical Physics, Faculty of Science and Technology, University of Debrecen, H-4002 Debrecen, PO Box 400, Hungary

  • *Contact author: csehi.andras@science.unideb.hu
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Phys. Rev. A 114, 033106 – Published 11 September, 2026

DOI: https://doi.org/10.1103/1tx6-b7lc

Abstract

Due to the recent availability of intense, short, XUV laser pulses, the investigation of the Autler-Townes (AT) doublet in resonant ionization phenomena is experiencing a renaissance. In particular, the asymmetry of the AT doublet was found to be sensitive to numerous physical parameters, providing a promising tool to probe and control the bound-state electron dynamics. Recently, the exact analytic evaluation of the AT doublet under rectangular pulse driving [A. Csehi, Phys. Rev. A 113, 033121 (2026)] provided a unified picture, revealing that the asymmetry is attributed to three main factors: (i) the interference of different ionization pathways, (ii) the distinct decay rates of the emerging dressed states, and (iii) the energy dependence of the bound-to-continuum couplings. Here, going beyond the constant envelope approximation, we identify the finite nature of the rising and falling edges of the laser pulse envelope function as an additional source of the asymmetry. Smoothly varying the envelope from a rectangular to a realistic pulsed profile (e.g., Gaussian), we show that the relative phases of the delayed photoelectrons, which are released at the temporal slits opened up by the Rabi cycling atom, can be efficiently modulated. This allows for the interference control of the electron yields at the main AT peaks. The found general asymmetry effect primarily hinges upon the asymmetry of the dressed-state energies in the continuum, caused by detunings or ac Stark shifts, and thus efficiently modified by the parameters of the laser, like intensity, photon frequency, and duration.

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Phys. Rev. A 114, 033106– Published 11 September, 2026
  • Received 5 June 2026
  • Accepted 27 August 2026
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