Control of interferences in an Autler-Townes doublet: Symmetry of control parameters

TLDR

The study demonstrates coherent control of the interferences and intensity of the two Autler‑Townes components in potassium photoelectron spectra using two intense, time‑delayed femtosecond laser pulses. Photoelectron spectra were recorded at various delays and laser intensities, and the quantum‑mechanical phase of the atomic state was symmetrically manipulated by strong fields or the optical phase of the delayed pulse. The experiments show that time delay and laser intensity play interchangeable roles for $(n+0.5)\pi$ excitation, the observations fit a two‑level model coupled to the continuum, and appropriate pulse combinations leave the excited‑state population unchanged.

Abstract

Coherent control beyond population control and spectral interferences is demonstrated on the interferences and intensity of the two Autler-Townes (AT) components in the photoelectron spectrum of K atoms, using a sequence of two intense time-delayed femtosecond laser pulses. Photoelectron spectra were taken at various delay times between the two laser pulses and at different laser intensities at a fixed delay time. With respect to the interferences in the AT doublet the role of time delay and laser intensity is interchangeable for $(n+0.5)\ensuremath{\pi}$ excitation. Strong laser fields or the optical phase of the delayed laser pulse allow the quantum mechanical phase of an atomic state to be manipulated in a symmetrical fashion. The observations are discussed in terms of a two-level model coupled to the continuum. For suitable combinations of the laser intensity of the first pulse and the time delay, the second laser pulse leaves the excited state population unchanged.