We propose a theoretical method to calculate the infrared (IR) laser-assisted photoabsorption cross sections over a broad energy range by a single calculation. In this method we define an initial wave function as the product of the dipole operator and the atomic ground state, propagate the initial wave function in the IR laser field with different initial phases, then calculate the generalized autocorrelation function, which is defined as the averaged value of the autocorrelation function over the initial phase from 0 to $2\ensuremath{\pi}$ (or one IR optical cycle). The IR laser-assisted photoabsorption cross sections are obtained by the Fourier transform of the generalized autocorrelation function. We apply this method to study the IR laser-assisted photoabsorption of He atoms. From the simulation results, we see that the IR laser field affects not only the resonant position but also the lifetime or the width of the bound states. This photoabsorption cross section is an important quantity to analyze the IR-laser-assisted dynamical processes by an attosecond pulse, a pulse train, or a free-electron laser.We propose a theoretical method to calculate the infrared (IR) laser-assisted photoabsorption cross sections over a broad energy range by a single calculation. In this method we define an initial wave function as the product of the dipole operator and the atomic ground state, propagate the initial wave function in the IR laser field with different initial phases, then calculate the generalized autocorrelation function, which is defined as the averaged value of the autocorrelation function over the initial phase from 0 to $2\ensuremath{\pi}$ (or one IR optical cycle). The IR laser-assisted photoabsorption cross sections are obtained by the Fourier transform of the generalized autocorrelation function. We apply this method to study the IR laser-assisted photoabsorption of He atoms. From the simulation results, we see that the IR laser field affects not only the resonant position but also the lifetime or the width of the bound states. This photoabsorption cross section is an important quantity to analyze the IR-laser-assisted dynamical processes by an attosecond pulse, a pulse train, or a free-electron laser.

Physical Review AJun 7, 201032 citations

Stark dynamics of two-electron atoms probed by scaled energy spectroscopy

Jeremy Murray-Krezan, J. Kelly, Mary R. Kutteruf +1 more

Orbital dynamics in two-electron alkaline earth atoms in a static electric field are studied using scaled-energy recurrence spectroscopy. Photoabsorption spectra for Ba and Ca Rydberg atoms are measured as continuous functions of static electric field and energy. In both Ba and Ca the laser excitation proceeds through the singly excited $nd$ series which is strongly perturbed by doubly excited valence configurations. Clear signatures of the two-electron dynamics associated with these perturbing configurations are identified.Orbital dynamics in two-electron alkaline earth atoms in a static electric field are studied using scaled-energy recurrence spectroscopy. Photoabsorption spectra for Ba and Ca Rydberg atoms are measured as continuous functions of static electric field and energy. In both Ba and Ca the laser excitation proceeds through the singly excited $nd$ series which is strongly perturbed by doubly excited valence configurations. Clear signatures of the two-electron dynamics associated with these perturbing configurations are identified.

Physical Review AJan 2, 20078 citations

Atomic photoabsorption process controlled by static and oscillating magnetic fields

Takeshi Shirahama, Xiao‐Min Tong, Ken-ichi Hino +1 more

We present a theoretical method to study atomic photoabsorption processes in a temporally periodic external field. The time development of the atomic dipole moment is propagated by numerical time propagation, and the photoabsorption cross sections is obtained directly from the Fourier transform of the autocorrelation function without summing up over the Floquet-Fourier components. As an example, we study the photoabsorption spectra of hydrogen atoms exposed in a mixture of static and periodically oscillating magnetic fields for the transition from $1s\ensuremath{\rightarrow}2p$. The atomic energy structure and photoabsorption spectra show interesting dependence on the strength of the oscillating magnetic field. Tuning the combination of the magnetic field strengths, we can control the photoabsorption process. The proposed method is general and can be applied to processes in which the number of relevant high harmonic components of the Fourier expansion is so large that the conventional Floquet method is intractable.We present a theoretical method to study atomic photoabsorption processes in a temporally periodic external field. The time development of the atomic dipole moment is propagated by numerical time propagation, and the photoabsorption cross sections is obtained directly from the Fourier transform of the autocorrelation function without summing up over the Floquet-Fourier components. As an example, we study the photoabsorption spectra of hydrogen atoms exposed in a mixture of static and periodically oscillating magnetic fields for the transition from $1s\ensuremath{\rightarrow}2p$. The atomic energy structure and photoabsorption spectra show interesting dependence on the strength of the oscillating magnetic field. Tuning the combination of the magnetic field strengths, we can control the photoabsorption process. The proposed method is general and can be applied to processes in which the number of relevant high harmonic components of the Fourier expansion is so large that the conventional Floquet method is intractable.

Physical Review AOct 23, 20096 citations

Laser Manipulation of Atoms and Ions

E. Arimondo, William D. Phillips, F. Strumia

Jan 1, 1992173 citations

nd

series which is strongly perturbed by doubly excited valence configurations. Clear signatures of the two-electron dynamics associated with these perturbing configurations are identified.