International workshop on theory for attosecond quantum dynamics (IWTAQD) 4

Jan16-Feb 4, 2012


Diection to UEC
English, Japanese

p1p2

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Participants (Bldg. E-6, Rms. 525, 527)

Oleg I. Tolstikhin Kurchatov Institute & MIPT
 Adiabatic Theory
 Jan16-Feb 4, 2012
Chiennan Liu Fu-jen University He dynamics under FEL Jan 30-Feb 10, 2011
Yasuo Okajima Nara Inst Sci & Tech
 HHG Jan 29-Feb 3, 2012
Hideki Ohmura AIST Polar molecules, two color laser Feb 3, 2012
Nguyen Ngoc Ty U of Tokyo HHG Feb 1, 2012
Kenichi Ishikawa U of Tokyo He dynamics Feb 1, 2012
Takeshi Sato U of Tokyo
 Multielectron molecular dynamics
 Feb 1, 2012
Misaki Okunishi Tohoku U Molecular imaging Feb 3, 2012
Linda Hamonou UEC Tunnel ionization of molecules
 Jan16-Feb 10, 2012
Michio Matsuzawa
 UEC
Feb 1, 3, 2012
Shinichi Watanabe
 UEC
Jan16-Feb 10, 2012
Toru Morishita UEC
 Chair
 Jan16-Feb 10, 2012
Vinh Trinh Hoai
 UEC Tunnel ionizatoin
 Jan16-Feb 10, 2012
Vinh Pham Nguyen Thanh
 UEC Rescattering
 Jan16-Feb 10, 2012
Masataka Ohmi
 UEC TDSE
 Jan16-Feb 10, 2012
Tomotake Yanakoshi
 UEC Cold atoms
 Jan16-Feb 10, 2012
Tsutomu Yamazaki
 UEC Low energy peak
 Jan16-Feb 10, 2012
Hsumin Hoang
 UEC 3-body break up
 Jan16-Feb 10, 2012
Osamu Ban
 UEC
Jan16-Feb 10, 2012
Kouki Kuromaru
 UEC
Jan16-Feb 10, 2012
Yoshimari Nasu
 UEC
Jan16-Feb 10, 2012
Kensuke Otani
 UEC
Jan16-Feb 10, 2012
Wataru Shimoaraiso
 UEC
Jan16-Feb 10, 2012

Seminar Program

Feb 1 (Wed) 14:30- 18:00 ' Laser-atom/molecule interactions & Cold collisions'
Place: Bldg. East 6, Rm. 803

Chair : T. Morishita
14:30-15:15
SPEAKER: Nguyen Ngoc Ty, The University of Tokyo, Department of Chemistry, Quantum chemistry laboratory
TITLE: Effect of nuclear vibration on high-order harmonic generation of H2+
ABSTRACT:
We present a fully quantum mechanical calculation of the harmonic spectra from vibrating molecule. By assuming the molecular ion H_2^+ is prepared in vibrational states, we show that in the case of weak pulsed laser, the HHG from higher vibrational levels have the higher intensity. However, when the intensity of laser pulse increases, the HHG from different vibrational states have nearly the same intensity. In addition, we point out that vibrational levels also influence on the position of minimum in HHG spectra due to the two-center interference.  The calculation shows the HHG spectra emitting from higher level of vibration have minimum at lower frequency.

15:15-15:45
SPEAKER: Yasuo Okajima, Nara Inst. Sci. & Tech.
TITLE: Adiabatic theory of high-order harmonic generation: One-dimensional zero-range-potential model
ABSTRACT:
We present a new analytical approach to high-order harmonic generation by a single atom. Since the electric field of the widely used intense laser beam changes slowly in time compared to the motion of the atomic electron, we set a theoretical framework in which the time development of the atomic system following the field is clearly decomposed to adiabatic and non-adiabatic ones. We first introduce an adiabatic parameter and then extract relevant physical quantities in terms of the order of this parameter using asymptotic analysis. As a first step in this approach, we examine a  one-dimensional zero-range potential as a model atomic potential, we also use the dipole approximation and the length form. Excellent agreement between the TDSE calculation and the
adiabatic theory will be demonstrated.

15:45-16:15
SPEAKER: Chiennan Liu, Fu-Jen catholic university
TITLE: Theoretical study of multi-photon double excitation of helium by intense ultrashort EUV pulses
ABSTRACT:
We present a theoretical study for multiphoton double excitation of helium atoms exposed to intense ultrashort extreme-ultraviolet pulses by solving the TDSE in hyperspherical coordinates, providing insights into a recent FEL experiment. Our results indicate that sequential multiphoton double excitation via bound Rydberg states are greatly enhanced, in comparison with direct multiphoton excitation, leading to large ionization yields through autoionization. Simultaneous excitation of more than one doubly excited state by a single ultrashort pulse creates an autoionizing two-electron wave packet, opening up the possibility of visualizing the correlated motion of electrons.

16:15-16:30 Break
16:30-17:15
SPEAKER: Oleg I. Tolstikhin, National Research Center "Kurchatov Institute" & Moscow Institute of Physics and Technology, Moscow, Russia
TITLE: Adiabatic theory of ionization of atoms by intense laser pulses
ABSTRACT:
In the laser-atom interaction problem, the adiabatic approximation  applies for sufficiently long wavelengths uniformly with respect to the amplitude of the laser field. A review of the first steps in the development of the adiabatic theory of ionization of atoms by intense laser pulses will be presented. The Keldysh theory and so-called strong field approximation is only a weak-field limit of the adiabatic theory.

17:15-17:30
SPEAKER: Satomu Yamazaki, UEC
TITLE: Low energy peak structure in photoelectron spectrum of hydrogen atom by ultrashort intense laser pulses
ABSTRACT:
We study the sharp peak structure observed in the low energy part of photoelectron spectra of rare gas atoms as well as di atomic molecules generated by intense mid-IR laser pulses. The peak structure cannot be explained by the so called Keldysh-Faisal-Reiss(KFR) theory, where the effects of target struacture are considered to be negligible. In the present  work, we study the photoelectron spectra of hydrogen atom by solving the time-dependent Schroedinger equation (TDSE). We analzse the low energy peak structure by changing the laser wavelength, the carrier envelope. Our calculations also show  that the low energy peak disappear for a short-range potential.

17:30-18:00
SPEAKER: Chen Zhang, U of Colorado
TITLE: Few-body ultracold reactions in bose-fermi mixture
ABSTRACT:
The spectrum of two bosons and two fermions in a trap is calculated using a correlated-Gaussian basis throughout the range of a broad Fano-Feshbach resonance. The calculations provide a few-body solution to the magneto-association of fermionic Feshbach molecules. This solution is used to study the time evolution of the system as the scattering length changes, mimicking experiments with Bose-Fermi mixtures near Fano-Feshbach resonances. The structure of avoided crossings in the few-body spectrum enables an interpretation of the dynamics of the system as a sequence of Landau-Zener transitions. The calculated molecule formation rate is compared with experimental observations.

18:15-
Free discussion at Rm 529




Feb 3 (Fri) 14:30-18:00 'Ionization dynamics'
Place: Bldg. East 6, Rm. 803

Chair : T. Morishita
14:30-15:00
SPEAKER: Misaki Okunishi, Tohoku University
TITLE: Rescattering Photoelectron Spectra of Molecules induced by intense ultrafast laser pulses
ABSTRACT:
We have observed rescattering photoelectron spectra of small molecules induced by intense laser pulses and found interesting interferences originated from electorn-ion scatterings. By comparing with the theoretically calculated differential cross sections of electron-ion scattering, we will show that the rescattering electron spectra contain rich information on the interaction between the electrons released by photoionization and parent molecular ions.
15:00-15:45
SPEAKER: Hideki Ohmura, National Institute of Advanced industrial Science and Technology (AIST)
               大村　英樹（独）、産業技術総合研究所（AIST）　計測フロン ティア研究部門
TITLE: Quantum control of molecular tunneling ionization by phase-controlled laser fields
         位相制御レーザーパルスによる分子トンネルイオン化の量子制御
ABSTRACT:
Intense (1012 - 1013 W/cm2) phase-controlled laser fields consisting of a fundamental light and a second-harmonic light induce directionally asymmetric tunneling ionization and the resultant selective ionization of oriented molecules. It is demonstrated that selective ionization of oriented molecules induced by phase-controlled ω+2ω laser fields reflects the geometric structure of the highest occupied molecular orbital. This method is robust, being free of both laser wavelength and pulse-duration constraints, and thus can be applied to a wide range of molecules.
レーザー光によって物質の量子状態および量子ダイナミクスを直接操作し、物性や機能をコントロールしようとする量子制御（またはコヒーレント制 御）に関する研究が近年精力的に行われている。我々は、波長の異なるフェムト秒光パルスを重ね合わせ、その相対位相を精密に制御した位相制御レー ザーパルスによる気体分子のトンネルイオン化の量子制御を実現した。位相制御レーザーパルスは従来の光とは本質的に異なった性質を持っているた め、光の位相に関わる新しい量子現象の観測、さらに位相制御レーザーパルスを用いた分子操作の新しい方法論を提示できる可能性がある。講演では強 いレーザーパルスによって引き起こされる気体分子のトンネルイオン化に関する最近の研究成果を紹介する。

15:45-16:15
SPEAKER: Linda Hamonou, UEC
TITLE: Study of Hydrogen molecular ion Siegert states in static electric field
ABSTRACT:
Over the past few decades the improvement in laser technology gave rise to an increasing interest in interaction light-matter. For a deeper understanding of the physical processes involved when matter is exposed to those radiations new theoretical methods are required.The Siegert state method was developed to study the ionization of molecule in static electric field.This new approach allows us to solve the Schrödinger equation for molecules irradiated by a static electric field and thus to obtain information on the ionization processand molecular structure dependent on the electric field, such as ionization rates and energy of a particular state.This method has the particularities to be able to take into account parameters such as the internuclear distance,the intensity of the electric field and more specifically the orientation of the molecule in the field. This last particularity of our approach give a new understanding of the importance of molecular orientation which hasn't been reached before. We studied the ground state and first excited states of the Hydrogen molecular ion H_2^+.

16:15-16:30 Break
16:30-17:15
SPEAKER: Kenichi Ishikawa, University of Tokyo
TITLE: Ionization of He by ultrashort extreme ultraviolet pulses
ABSTRACT:
We discuss two-photon single and double ionization of He by attosecond and femtosecond extreme ultraviolet pulses, by use of direct numerical solution of the two-electron time-dependent Schrödinger equation.

17:15-18:00
SPEAKER: Takeshi Sato, University of Tokyo
TITLE: Multi-electron dynamics in intense laser fields: Simple multi-configurational time-dependent approaches
ABSTRACT:
Time-dependent Schrodinger equation (TDSE) exactly describes the dynamics of atoms and molecules in intense laser fields, but is too costly to be applied to multi-electron systems. Approximate yet multi-electron time-dependent theories are required, bridging the gap between TDSE and simplified models. In this work, we propose simple multi-configurational time-denendent approaches based on the concepts of the generalized valence bond theory (TD-GVB). We present the structure of the wavefunction, the equation of motion, and some numerical results for exactly solvable problems such as one-dimensional He model.

18:30-
Free discussion, the place to be announced




Toru Morishita,UEC