The investigation of nuclear processes in femtosecond laser plasma is under intensive study in the last time [1,2]. The first successful observation of excitation and decay of 6.238 keV Ta-181 isomeric level [3,4] has stimulated interest to this specific nuclear transition [5,6]. The theory of nucleus excitation by blackbody x-ray emission of stationary laser plasma has been discussed earlier [3,4,7]. However the experimentally registered efficiency of excitation exceeds the theoretical calculations. There are a number of possible reasons that explain this difference. The first possible reason can be associated with the different mechanisms of nuclear transition broadening. Indeed, the expansion of laser plasma results in the appearance of the quasi-static electric and magnetic fields. The simple estimations show that the inhomogeneous line-width due to the quasi-static fields in laser plasma can exceed the Doppler broadening. However, the blackbody emission is s-correlated and integration over the inhomogeneously broaden spectrum of nuclear transition results in the efficiency of excitation which is quite closer to the efficiency of excitation for homogeneously broaden transition. Here we study the influence of the non-stationary manner of bremsstrahlung by hot electron component of laser plasma on the efficiency of radiative channel of nucleus excitation in laser plasma. The main idea of proposed explanation is in the following. The process of inelastic collision of electron and ion in laser plasma has a finite duration. It is natural to assume that it is this time that determines the spectral width of x-ray bremsstrahlung emission. For the hot electron component the characteristic temporal interval of inelastic collision is less than 0.1 fs. Thus, the coherent bandwidth is comparable with the frequency of bremsstrahlung peak intensity. As a result the account of the finiteness of the bremsstrahlung correlation time can significantly affect on the calculated efficiency of excitation.

Analyzing influence of band structure of a crystalline solid on ionization rate we have discovered a new regime of ionization referred to as collective one. It cannot be discovered in the framework of traditional approaches to analysis of ionization since they are based on specific band-structure models describing only the central part of the first Brillouin zone. To reveal and to study the effect we reformulated the Keldysh calculation procedure for the case of cosine energy-momentum relation and derived an expression for the corresponding ionization rate. Results of the calculations show occurring of a singularity on dependence of the ionization rate on laser intensity with the ionization rate increasing up to infinity. The singularity has a well-defined threshold that was rigorously calculated and shown to be close to 10 TW per square centimeter for many wide band-gap dielectrics. The singularity is associated with the collective ionization corresponding not to individual "electron-by-electron" inter-band transitions, but to collective inter-band jumps of electrons. We relate its physical mechanism to Bragg-type reflections of oscillating electrons at boundaries of the first Brillouin zone. They result in specific redistribution of pondermotive energy among the oscillating electrons in such a way that the total energy of an electron does not depend on its initial quasi-momentum, i.e., it is homogeneously distributed over all states in the Brillouin zone. The latter effect is referred to as flattening of the effective band.

The results of theoretical investigation of processes resulting from disturbance of charge equilibrium in a solid nanoparticle, induced by fast ionization under high-intensity ultra-short laser pulse action are presented. Analytical and numerical methods were used to study time evolution of space and energy distributions of moving ions during their spreading away from the particle for various sizes and shapes of the particle as well as various degrees of ionization of its material. The final aim of the presented study is to analyze the influence of the disturbance of charge equilibrium induced by high-intensity ultra-short laser pulses in a solid on parameters of laser-induced damage of the material, and the regularities of the atoms and ions motion of the media in damage area under the action of local laser-induced Coulomb potential.

The possibility of electron acceleration during the laser radiation relativistic and charge-displacement self-channeling is studied theoretically. A new acceleration mechanism related to the formation of an ion cloud traveling in a matter with the laser pulse (due to the effect of the ponderomotive force) is considered. The quasistationary electric and magnetic fields generated by the moving ion cloud may accelerate electrons to energies of tens of MeV and result in the formation of an electron beam going forward coaxially with the laser pulse. The angular distribution of accelerated electron calculated matches the experimental results found in the available publications.

New mechanism of laser acceleration of a charged particle is studied. We found that particle acceleration with focused beam of superintense ultrashort laser pulse is determined by a combination of ponderomotive forces at rising and falling edges of laser pulse and a longitudinal component of laser electric field. Acceleration of electron, which moves along the laser wavevector, is crucially depends on whether or not the electron reaches the region behind the laser focus. Interpretation of this effect consists in that the laser longitudinal electric field at the electron trajectory in this region is a unidirectional one (oscillatory in the case of laser linear polarization and slowly varying in the case of laser circular polarization). Due to this effect it is possible to overcome the negative influence of a phase slippage in the particle-wave interaction, which substantially suppresses electron acceleration. The physical reason of a unidirectional influence of laser longitudinal electric field on accelerating electron consists in the difference in phase velocities of transverse and longitudinal components of a focused laser field. Owing to this mechanism, lasers of ultimate present-day parameters enable electron acceleration up to the energy ε ~ 1 GeV. Moreover, electron acceleration along the laser wavevector (in contrast to techniques currently considered) is not sensitive to field initial phase (there is no bunch effect), it is possible to accelerate slow electrons (electrons need not to be preaccelerated to relativistic velocities), and there are no problems with a removal of accelerated electron from the laser field.

We report the observation of self-guided propagation of 120 fs, 0.56 mJ infrared pulse in air for distances greater than a meter (more than thirty Rayleigh Lengths). The numerical simulations demonstrates the this localized structure corresponds to a Townes soliton, specially stable under these conditions.

In the non-relativistic limit, the dynamics of the interaction of light with matter is described via a Hamiltonian that does not include spin operators. However, the actual spin configuration of the interacting particles still plays a fundamental role, via the Pauli's exclusion principle, by forcing a particular symmetry of the spatial part of the wavefunction. In this paper we analyze the role of symmetry in the process of ionization of two and three-electron atoms.

The dependency of the maximum ion energy emitted to rear side of a thin film on laser pulse duration was described by isothermal plasma expansion model, and the maximum proton energy was increased with pulse duration. 1 MeV protons were obtained with laser energy of 30 mJ by optimizing focusing using adaptive optics.

The simple analytical formula for description of the scattering of the laser radiation ultrashort pulse with the shape of the Meyer wavelet by atomic system is obtained. The dependence of the scattered pulse shape as a function of the system spectral width is discussed.

It was examined a behavior of highly excited states of atoms in a strong electromagnetic field. A fulfilled consideration has shown necessity to correct take into account of the influence of multiparticle effects on a spin-orbital interaction of matter with a superintensive electromagnetic field.

The results of the theoretical consideration and two dimensional Particle in Cell simulation of electron acceleration with a short-pulse intense laser propagating through a finite length underdense plasma layer are presented. The fast electron energy spectrum and emittance are analyzed for moderate to high intensity and for different plasma density. It is shown that for laser pulse lengths above the plasma wake wavelength the wake field accelerated electrons are further accelerated by the electromagnetic wave.

We rejort on the experimental realisation of time-resolved coincident Coulomb explosion imaging of H2-fragmentation in 10¹⁴ W/cm² laser fields. Combining a high-resolution 'reaction microscope' and a fs pump-probe setup, we map the motion of wave packets dissociating via one- or two-photon channels, respectively, and observe two region of enhanced ionization in accordance with earlier theoretical predictions. The long-term interferometric stability of our system allows us to extend pump-probe experiments into the region of overlapping pulses, which offers new possibilities for the manipulation of ultrafast molecular fragmentation dynamics.

We present results of high resolution fully differential measurements on single ionization of He, Ne, and Ar by 7-25 fs linearly polarized 800nm laser pulses at intensities of up to 2^.10¹⁵ W/cm². Using a 'Reaction-Microscope' we were able to trace signatures of multiphoton ionization deep into the tunnelling regime. Surprisingly, in the low-energy electron spectra we observed several features (absence of the ponderomotive shifts, splitting of the peaks, their degeneration for few-cycle laser pulses) typical for resonantly-enhanced ionization. Other remarkable features, as the sharp cusp-like momentum distributions in the direction perpendicular to the laser field or the observed minima at zero longitudinal momentum for He and Ne, can be reproduced by semiclassical models, where the electron motion in the combined laser and Coulomb field is treated classically after the tunnelling.

It has been shown, that usage of the certain initial phase modulation of fundamental laser pulses is capable to result in increase of pulse compression efficiency in type II second harmonic generation. The variations ofinitial phase modulation of the fundamental laser pulses expand optimal ranges ofthe nonlinear medium and laser radiation parameters needed for efficient pulse compression.

Experimentally it was shown that liquid gallium can be used as a target for 10 Hz femtosecond laser plasma x-ray source. X-ray measurements demonstrated that temperature of hot electrons in gallium plasma does not differ from plasma of solid target and equal to 6.2±1.OkeV.

Experimental and numerical investigations of femtosecond laser plasma at the cleaned surface of crystalline Si and w targets are carried out. The constructed picture of ionization, acceleration and recombination of ions in plasma well explains main features of atomic, charge and energy spectra of fast and slow ions.

We show the generation of intense isolated pulses from a single harmonic (photon energy 27.9 eV) by using sub-lO-femtosecond blue laser pulses. Nonadiabatic evolution of the blue laser pulse produces a large dipole moment at the relatively low (ninth) harmonic order and the ionization of neutral gas interacting with the laser electric field shortens the harmonic pulse duration, resulting in the high peak intensity at a focus of the high harmonic light field. By virtue of the high peak intensity of the generated harmonic pulse, nonlinear optical pprocess in the extreme ultraviolet (XUV), i.e. two-photon above threshold ionization (ATI), was successfully observed. The XUV pulses with temporal durations of 950 attoseconds and 1.3 femtoseconds were characterized by an autocorrelation technique, based on two-photon ATI of helium atoms. Because of the small cross-section for above-threshold ionization, such an autocorrelation measurement of xUv pulses with photon energy larger than the ionization energy of helium has not hitherto been demonstrated. The technique can be extended to the characterization of higher harmonics in shorter wavelengths.

The possibility of generation of attosecond pulses of recombination radiation upon the above-threshold tunnel ionization of atoms (ions) in two-color laser fields is studied. The method of classical photoelectron trajectories in the contmuum is used to detennine the laser field parameters minimizing the duration of recombination radiation. It is shown that pulses of duration of several tens of attoseconds can be generated in such fields. The principal possibility of generation of coherent electromagnetic pulses of duration τ_g⪅1 as is also shown.

The resonance generation and propagation of single as well as double attosecond pulses with TW-intensity in Ar⁺ are presented by the numerical simulations. Two-photon Raman-type self-induced transparency of the pulses is investigated.

We present the theory of the attosecond pulse generation by a relativistically intense few-cycle laser pulse interacting with a thin plasma slab. In the limit of high plasma density or in the case of two identical pulses irradiating plasma from opposite sides, the electron displacement in the direction perpendicular to the plasma slab is negligible. Electrons moving along the plasma slab form the sliding mirror. The relativistic dynamics of the electrons result in the generation of the phase-locked high order harmonics. After spectral filtering, isolated attosecond pulses with the duration less than 200 as can be obtained. We also find a very efficient regime of the attosecond pulse train generation without any spectral filtering with the energy conversion efficiency into the main peak of about 3%.

High harmonics produced in aligned molecules contain the structural information of bound-state electronic states. We have produced high harmonics from N₂ molecules aligned to arbitrary directions with 5-degrees steps. From the set of high harnionic spectra, we have successfully reconstructed tomographic images of the highest occupied molecular orbital (HOMO) of N₂.

A theoretical study is presented suggesting possible photoelectron spectroscopy measurement of electron dynamics on molecules on "attosecond" time scales. In particular, we study analytically the photoionization of a coherent superposition of molecular electron states by an ultrashort, attosecond X-ray pulse. We show that the broad photoelectron spectrum inherent in attosecond pulse ionization contains detailed information about the time-dependent electron wave packet. Such ultrashort pulse photoionization leads to an asymmetry of the photoelectron momentum distribution and this seems to measure the momentum asymmetry of the initial coherently prepared electron bound state. We show further that universal molecular Coulomb interference effect occur in ultrashort pulse photoionization and other processes with fast momentum transfers. Thus "attosecond" photoelectron spectra and their inherent asymmetry allow to monitor and in principle to control electron motion on the attosecond time scale.

We present a method for creation a slow velocity (12 mIs) atomic beam with high atomic flux (7.2 10¹² atoms/s) based on the Zeeman slowing technique ofthermal ⁸⁵Rb atoms in the transversal magnetic field and use of 2D MOT technique.

We present an effective atomic beam splitter based on the interaction between three-level atom and the field of the standing optical waves with relative spatial shift φ=π/2. We show that using of several interaction zones of the standing waves with the different spatial shift it makes possible to reach the splitting 2n&barh;k (where n is the number of zone) in each of lower three-level Λ-atom state.

In this paper a system of two qubits interacting with common broadband thermostat was investigated. We managed to gain problem parameters witch can produce stationary entanglement from initially unentangled quantum states. It was also found out that it is possible to adjust the measure of entanglement by varying problem parameters, and it can be said that our methods are considered to be suitable for generation of entanglement with any pre-defined value. Our previous results were extended in this paper, and we are up to show that stationary states ofthe system have non-trivial dependence on initial conditions, witch are more complicated then it was previously reported.

By solving the self-consistent system of Maxwell and derithty matrix equations in the case when the relaxation time is much shorter than the pulse duration, we obtain an analytical solution for the probe pulse propagation. This solution allows one to analyze the process of the information storage not only qualitatively, but also quantitatively In particular, it explains the fact that in well-known experiments only fractions of pulses were stored The conditions for effective storage are obtained.

It is known that solitons of Bose-Einstein condensates with positive scattering lengths can be produced in optical lattices. The key of this process is the negative sign of the effective mass of the wavepacket as it comes closer to the edge of the first Brillouin zone. However, the underlying assumption of the effective mass approach is the slow variation of the wavefunction envelope between consecutive lattice cells. Previous experiments and computations on this type of solitons show that this is not the usual case. In this contribution we will go beyond the slowly varying assumption to demonstrate that the equations governing the dynamics of gap solitons contain a third derivative in the dispersion. As a result, the dynamics of the stabilized wavepackets is found different that the soliton's. In particular, a radiative component is present, and the stability under collisions is only partially achieved.

We have observed Bose-Einstein condensation of chromium atoms [1], whose large magnetic dipole moment is unique among all species that have been Bose-condensed so far. The arising magnetic forces are of anisotropic and long-range character and therefore introduce a novel type of interaction in the physics of ultracold quantum gases. In addition, it is expected that the character of the interaction present in a chromium BEC can be varied from mainly contact to purely dipolar utilizing one of the recently observed Feshbach resonances in ⁵²Cr-collisions.

When two of three pairs of the Gaussian laser beams of a traditional MOT are misaligned in the "racetrack" configuration the effective coordinate-dependent vortex force do arise. Then an atom is accelerated by this vortex force until its velocity not balanced by the damping force. This situation may produce a stable ring of revolving atoms of a certain radius. Due to the different frequency and laser beams intensity dependences of the vortex, damping and trapping forces it is possible to equalize the radii of two orbiting groups of atoms in two-species or dual-isotope magneto-optical trap and so to arrange a continuing collider of cooled atoms with the prescribed relative velocity. A collider setup for atoms of two different types rotating with different angular velocities along the same ring-like trajectory into MOT of the conventional six-beam geometry is proposed and designed on example of two rubidium isotopes Rb85 and Rb87.

We study the absorption properties of a weak probe field in a four-level atomic system. By employing a strong driving field, we investigate the Electromagnetically Induced Transparency (EIT) in this system. We show that, in certain condition, the absorption peak vanishes and the medium become transparent to the weak probe field.

We present both analytical results and numerical simulations that describe the light pressure on atoms in the fields of counterpropagating waves whose amplitudes and phases are described as stochastic processes. We show that, just as with the light pressure exerted in the field of two counterpropagating bichromatic waves, the light pressure on an atom in counterpropagating stochastic waves may considerably exceed the pressure exerted in the field of a single running wave, when one of them repeats the other with some delay, We also discuss the interaction of an atom with two counterpropagating waves when one of them is monochromatic and the other one has a stochastic phase.

The quantum aspects like entanglement and quantum distances between quantum states in the Stimulated Raman Scattering (SRS) process are studied using the simpliest model of two-dimensional oscillator with quadratic interaction. The two modes of the oscillator represent the photons of the Stokes mode and the phonons of the medium respectively. The SRS process is discussed in the probability representation of quantum mechanics. The exact formulae for tomograms are given for the symplectic and photon number tomography schemes. The phenomenon of entanglement is investigated. It is shown that after the interaction of laser field with the medium the state of photon-phonon mode is in entangled states, in view of Peres-Horodecki-Simon criterion. The tomographic entropy associated with photon-phonon mode state is introduced. The quantum distance between the states of photon-phonon mode appearing in the case of different initial states of the medium is discussed.

The indirect aftractive interaction between the electron and holes lying on the lowest Landau levels on the surface of a two-dimensional structure in the presence of a strong perpendicular magnetic field appears due to their virtual quantum transitions to excited Landau levels as a result of the Coulomb scattering. The influence of this indirect interaction on the ground state energy and on the chemical potential of the Bose-Einstein condensed magnetoexcitons is determined. The corrections to the energy spectrum and to the wave function of the lowest magnetoexciton band due to the influence of the first three excited exciton bands were investigated.

Quantum correlations and entanglement are an important addition to the conventional properties of continuous laser beams. They allow us to avoid, at least in principle, the limitations imposed by quantum noise and they open new opportunities for the transfer and processing of quantum information. This manuscript reviews the state of art in the creation, detection of quantum correlations and entanglement, shows the analogy to the techniques based on single photons. It summarizes some of the recent advances in optical sensing and quantum information processing.

We give a definition of asyimnetric universal entangling machine, entangling a system in an unknown state to a specially prepared ancilla. We describe explicitly such a machine for a d-level quantmn system and prove its optimality.

Atomic ions confined in segmented trap arrays provide a system for quantum information processing. We report on the execution of two simple quantum algorithms, quantum error correction and the quantum Fourier transform, using this implementation. The demonstration of these algorithms in a scalable system is one step towards the execution of useful, large-scale quantum algorithms.

Information aspects of copying quantum states via stimulated emission of an optical quantum amplifier are considered. It is shown that the measurable information very rapidly decreases after amplification of a single photon up to a level of several photons. Spontaneous emission, which leads to such behavior, is also discussed.