Objectif The project is dealing with the interaction of atoms with intense ultrashort light pulses and specifically with High-Harmonic Generation (HHG) and Above-Threshold Ionisation (ATI).First, it explores novel approaches to the theory of HHG with the goal of improving the understanding of this process and achieving higher conversion efficiencies. Second it investigates the ionisation process in the tunnelling limit.The objectives include:To validate the concept of amplification of a high harmonic wave propagating through an atomic medium simultaneously irradiated by an intense infrared beam, to make quantitative predictions and to calculate and measure the gain;To investigate HHG by two coherent laser beams with equal frequencies propagating in slightly different directions. The goal is to establish the new phase-matching condition and to optimise and control the harmonic intensity by varying the angle between the incident waves with fundamental frequency;To calculate the duration of a high harmonic radiation pulse by using the quantum radiation theory approach. The goal is to compare results and interpretations following from the new approach and existing theories;To obtain analytic expressions for the quantum distributions in the tunnelling limit of high-order ATI and HHG by individual atoms in an elliptically polarized laser field;To investigate the influence of the detailed shape of the atomic binding potential on HHG and ATI.The project involves experimental and theoretical research. The novel physical ideas stated in objectives 1, 2 will be investigated both experimentally and theoretically. Experiments related to these objectives will be carried out in Saclay while the MBI team and the NIS teams provide the relevant theory. These teams will, as well, be involved in theoretical investigations on the quantum theory of the HHG by individual atoms and on the quantum interference effects in the high energy ATI.The expected resultsThe quantum theory of HHG and a quantitative prediction of the gain.Experimental set-up allowing to amplify a harmonic wave travelling through the interaction volume pumped by a laser with the fundamental frequency.A measured value of the gain of a harmonic wave.The phase-matching condition in the case of two non-collinear pump waves.A practical method allowing to optimise and control the harmonic intensity by varying the angle between the incident waves with fundamental frequency.The relationship between the quantum and semi-classical approaches to HHG.A set of approximate analytic formulas describing HHG by individual atoms and the high -energy part of the photoelectron distribution in elliptically polarized field taking into account quantum interference effects.Established properties of high harmonic generation and above-threshold ionisation which essentially depend on the particular shape of the atomic potential and criteria of that influence. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) 1B - Condensed Matter, Optics and Plasma Physics OPEN - OPEN Call Appel à propositions Data not available Régime de financement Data not available Coordinateur Commissariat à l'Energie Atomique Contribution de l’UE Aucune donnée Adresse Centre d'Etudes de Saclay 91191 Gif-sur-Yvette France Voir sur la carte Coût total Aucune donnée Participants (3) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Max-Born Institute of Nonlinear Optics and Spectroscopy Allemagne Contribution de l’UE Aucune donnée Adresse Rudower Chaussee 6 12489 Berlin Voir sur la carte Coût total Aucune donnée Russian Research Center "Kurchatov Institute" Russie Contribution de l’UE Aucune donnée Adresse Ploschad Kurchatova, 1 123182 Moscow Voir sur la carte Coût total Aucune donnée Technical University Russie Contribution de l’UE Aucune donnée Adresse Kashirskoe shosse, 31 115409 Moscow Voir sur la carte Coût total Aucune donnée