Maria V. Ryabinina

Phase‐Sensitive Ionization and Recombination of Anti‐Hydrogen Atom Using Zero‐Duration High Intensity Laser Pulse

Theoretical non‐perturbative calculations of transition amplitudes for arbitrary initial and final states of (anti)hydrogen atom induced by ultra‐short laser pulse or sequence of pulses are presented. The dependence of transitions probability (in discrete spectrums, ionization and recombination) on the laser pulse strength is shown.

Polarization transverse pattern dynamics in lasers with anisotropic cavities

Polarization transverse pattern dynamics in lasers with an image-rotating cavity is studied taking the Zeeman sublevel structure of the lasing transition into account. For a class-A laser with an arbitrary transverse mode number, the field dynamics and the regimes of oscillations have been investigated numerically.

Dynamics of polarization transverse patterns in lasers

Short review of the papers on transverse and polarization transverse pattern dynamics in lasers is presented. The theoretical and numerical models are discussed including cavities with image rotation and allowing for the Zeeman sublevels structure of the lasing transition. The results of numerical modelling of the field dynamics, oscillation regimes, and effect of the spontaneous emission on the pattern resulted are presented and discussed for the class A lasers with the polarization isotropic cavity and unlimited transverse mode number.

Coherent effects in free-bound transitions in hydrogen/antihydrogen atom under the action of ultra-short strong-field laser pulse

Using discrete approximation of the continuous levels in H-atom the nonperturbative probability amplitude equations for 1s state and groups of continuous levels coupled via laser resonant pulse were solved numerically. The coherent Rabi-like population oscillations of 1s -state are observed. The role of free-free transitions, optimum pulse area and other parameters for recombination are discussed.

Polarization transverse-pattern dynamics in lasers and their classification based on the characterization of its singular points

Vectorial Karhunen-Loeve modes were used for the description of the polarization transverse pattern dynamics of the Zeeman multitransverse mode layer with large Fresnel number and anisotropic cavity. Stokes parameter distribution of the laser field in the transverse plane define new 2D vector field. Catastrophe theory and Newton diagram method were used for the classification of the laser field based on the characterization of the 2D vector field behavior in the vicinity of its singular points in the transverse plane. The results of numerical experiments show that the regimes with rotating patterns are closely connected with An catastrophe functions of argument r equals (root)(x2+PLUy2), where x,y are the transverse coordinates. For the oscillating patterns the regimes can be classified using Newton diagrams which are also connected with corresponding polynomials.

Polarization-dependent laser-induced orientation in antiprotonic helium

Laser-induced orientation and population dynamics in antiprotonic helium under the action of a short laser pulse are studied numerically to investigate polarization effects. Stimulated transition from the metastable long-lived state to the Auger-decayed state is considered, taking into account the Zeeman structure of the levels. The regimes when nearly all atoms can be transferred to the lower level (similar to a π-pulse in a two-level system) are demonstrated.

Laser-induced antiproton-positron recombination

The most favorable conditions for positron-antiproton capture in traps can be provided when high-density clouds of accumulated antiprotons and positrons are brought and kept together by means of specially chosen electromagnetic field and strong cooling. However, the cross-section of the spontaneous recombination remains very small even at extremely low temperatures. The recombination rate may be increased in an external resonance field. In the present report the possibility of increase the recombination rate by means of laser pulses is estimated. An initial state of antiproton-positron system will belong to a continuous spectrum final state and to a discrete one. Taking into account the possibility to use short pulses, we analyzed system state after the laser pulse.

Nonlinear polarization phenomena in lasers with anisotropic cavity

In the present paper the polarization-transverse patterns in the multimode vector-field laser with no restriction imposed on the transverse mode number are studied numerically using the dynamical model, in which the saturation of the working transition is described analytically. We considered a unidirectional ring cavity with image rotation. The active medium of the laser is assumed to be homogeneously broadened. The Zeeman splitting of the active transition controlled by the axial magnetic field was taken into account. The medium polarization and levels population is assumed to be adiabatically eliminated (class-A laser). The vector-field catastrophes were used for the description of pattern dynamics.