International workshop on theory for attosecond quantum dynamics (IWTAQD) 19

June 18 - July 13,  2018


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

Oleg I. Tolstikhin MIPT
Adiabatic Theory, Tunneling ionization
Jun 18 - Jul 7, 2018
Chiennan Liu Fu-jen catholic U He dynamics under FEL/IR laser fields
Jul 3-13,  2018
Akiyoshi Hishikawa Nagoya U FEL, Molecular dynamics
Jul 2-3, 2018
Kenta Kitano
Aoyama Gakuin U
Atomic coherent contol
Jul 3, 2018
Shinichiro Minemoto
U of Tokyo
FEL experiment
Jul 3, 2018

Jens Svensmark UEC
Molecular dynaimcs in intense laser fields
Jul 3 - Jul 13, 2018
Tor Kjellsson Lindblom UEC
Atomic tunneling ionization
Jun 18 - Jul 13, 2018
Shinichi Watanabe
UEC Many body physics Jun 18 - Jul 13, 2018
Toru Morishita UEC
Jun 18 - Jul 13, 2018
Shun Ohgoda    
TDSE/Static Field Induced States   
Jun 18 - Jul 13, 2018

Hirokazu Matsui UEC Siegert states, Adiabatic transition, Tunneling ionization
Jun 18 - Jul 13, 2018
Jargalsaikhan Amgalan
UEC Intense laser physics
Jun 18 - Jul 13, 2018
Hisashi Ishinoda
UEC Intense laser physics Jun 18 - Jul 13, 2018
Yushiro Suzuki
UEC Intense laser physics Jun 18 - Jul 13, 2018
Shunsuke Inoue
Intense laser physics Jun 18 - Jul 11, 2018

Seminar Program

Jul 3  (Tue) 2018
Place: Bldg. East 6, Rm. 803


  Pavel K. Samygin, Toru Morishita, and Oleg I Tolstikhin (MIPT)
"Weak-field asymptotic theory of tunneling ionization from nearly degenerate states
The weak-field asymptotic theory (WFAT) of tunneling ionization in a static electric field is limited by the assumption that ionization occurs from an isolated state. In this paper, we generalize the WFAT in two directions: to the cases when tunneling ionization occurs from (1) nearly degenerate states separated by a small energy distance E in compact atomic or molecular systems, and (2) an isolated state in dissociating heteronuclear diatomic molecules at large internuclear distances R. The weak-field asymptotic formulas for the ionization rates in these two cases are obtained. The asymptotics are uniform with respect to
E and R and for sufficiently large E and small R, respectively, reduce to the previous WFAT rate formula. By combining the two asymptotics, we obtain a formula for the ionization rate from a pair of nearly degenerate 1sg and 2pu states of a homonuclear molecular ion H2+ at large internuclear distances, which is of particular interest for applications in strong-field physics. The analytical results are illustrated and validated by calculations for several atomic and molecular models.

10:40-11:20  Shinichiro Minemoto (U of Tokyo)
"Time-resolved photoelectron spectroscopy of atoms and molecules using EUV-FEL and ultrashort laser pulses"
Recently SACLA, the free-electron laser facility in Japan, has started to provide FEL pulses in the extreme ultraviolet regions with photon energies below 150 eV. With the EUV-FEL pulses, we are conducting experiments synchronized to optical laser pulses. So far, we have succeeded to observe sidebands in photoelectrons of Ar, which ensures temporal overlap between FEL and optical pulses. We have also measured angular dependences of photoelectrons from CO2 molecules nonadiabatically aligned by an optical laser field. I will discuss the futures of pump-probe photoelectron experiments using the EUV-FEL.


Kenta Kitano (Aoyama Gakuin U)
"Spatiotemporal profile of yoked superfluorescence from Rb vapor in the strong excitation regime "
When a dense atomic sample is prepared with a coherent superposition of upper and lower states in a three-level system, the excited atoms quickly decay to the intermediate state with an emission of a superfluorescent pulse, which can induce the transition between the intermediate and ground states, resulting in a highly directional emission. This coherent interplay between the upper and lower transitions is called yoked superfluorescence(YSF). We investigated the YSF from atomic vapor of rubidium(Rb) by driving the 5S|5D two-photon transition with an ultrashort laser pulse. By increasing the pump-pulse power beyond the saturation intensity, the spatial profile of the emission from the lower transition component of the YSF periodically changed between a central bright spot and a ring-shaped radial profile. The observed behavior was successfully explained by a nonlinear response of Rb atoms to the pump field.

14:10-14:50 Kiattichart Chartkunchand (RIKEN, Stockholm U)
Studies of Long-Lived Negative Ion Metastable State"
Negative ions have long been fascinating systems to study, as they are a testament to the subtle nature of electronic structure and dynamics on the atomic scale. Their very existence is strongly governed by complex electron correlation effects, resulting in systems with relatively low ground state binding energies and few if any bound excited states. In many cases, bound excited states in negative ions are of the same parity as the ground state, resulting in long-lived metastable states with lifetimes that can range from tens of microseconds to several hundred seconds. Studying negative ion metastable states and properties such as their lifetimes can aid the theoretical understanding of the correlation effects that give rise to them. Such measurements can provide critical benchmarks for theoretical methods treating these effects in negative ions and more general atomic and molecular systems. Experimental studies of negative ion metastable state lifetimes have been greatly enhanced in recent years by the emergence of cryogenic electrostatic ion storage devices such as ion traps and storage rings. These devices have allowed for storage of ions up to thousands of seconds in environments with residual gas densities approaching those of the interstellar medium and greatly reduced influence of thermal blackbody radiation. Several pioneering studies were conducted at the DESIREE facility at Stockholm University [1], the worldfs first cryogenic electrostatic ion storage ring. An overview of some of these experiments will be presented, as well as prospects for future experiments using the worldfs newest and coldest cryogenic storage ring, the RIKEN Cryogenic Electrostatic (RICE) ring [2].

[1] R. D. Thomas et al., Rev. Sci. Instrum. 82, 065112 (2011)
[2] Y. Nakano et al., Rev. Sci. Instrum. 88, 033110 (2017)


Akiyoshi Hishikawa (Nagoya U)
"Three-dimensional photoelectron momentum imaging of atoms and molecules in circularly polarized intense laser fields"

Three-dimensional photoelectron momentum distributions of Ar, D2, O2 in circularly polarized intense laser fields (800 nm, 1014 W/cm2) have been recorded by an electron-ion coincidence momentum imaging setup. Their properties and the field intensity dependence will be reported.

15:50-16:20  Tor Kjellsson Lindblom (UEC)
Towards constructing atomic Siegert states in a circularly polarized laser field in a rotating frame"

Siegert states are solutions to the stationary Schrödinger equation satisfying regularity and outgoing-wave boundary conditions. They constitute a powerful tool in understanding ionization by static electric fields, and have been applied to ionization by intense linearly polarized laser pulses in the newly developed Adiabatic theory of photoionization [1]. Efforts are now being made to apply this theory to the case of intense circularly polarized pulses (ICPs). The first building block of such a theory is the corresponding Siegert states in a frame co-rotating with the polarization vector of the pulse. In this talk I will give a short introduction of our approach to obtain these, and show preliminary results of ionization rates of an electron initially bound by a Finite-range potential, exposed to different monochromatic ICPs.

Ref 1:
Adiabatic theory of ionization by intense laser pulses: Finite-range potentials,
O. I. Tolstikhin and T. Morishita, Physical Review A 86, 043417 (2012)

@Jens Svensmark (UEC)
"Theoretical study of molecular ionization including nuclear motion"
Within strong-field physics, ionization is an important fundamental process. We are seeking to extend to the adiabatic theory developed in [Phys.  Rev.  A  86,  043417  (2012)] to include nuclear motion in the description of ionization. As a first step towards achieving this goal, we are currently working on getting accurate reference solutions to the TDSE, against which results from the adiabatic theory can be compared. In this talk I will give a status report on our work towards this.


Toru Morishita,UEC