Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Coherent control of photoionization of atomic barium

Rekishu Yamazaki

Published Jan 1, 2006• 0 citations
OpenAlex

Abstract

We present the results of our study on coherent control of photoionization of atomic barium. Our study focused on the understanding of the controllability, especially due to the effect of the coherent interaction between the atomic system and the laser field. The first half of the study investigates the mechanisms of the control behind the previously observed laser phase-insensitive product state control. The controllability of this excitation scheme, two-color two-photon resonantly enhanced excitation, was analyzed from two aspects, the role of ac Stark shift introduced by the strong laser field and the multi-pathway quantum mechanical interferences. We have analyzed the excitation scheme from the analysis of the photoelectron angular distribution measured using the excitation scheme and the monitoring of the intermediate state population. Analysis of the data as well as the numerical simulation showed clear understanding of the role of two mechanisms in the product state control reported. We also investigated the control of the phase lag during the product state control. We conducted the control of the phase lag in the study of asymmetric photoelectron angular distribution, which arises from the concurrent even-odd parity outgoing electron wave excitation. The phase lag was controlled in full range, 2π, and the results were analyzed in terms of the role of autoionizing resonance structures as well as the nature of outgoing electron waves at different locations of the autoionizing resonances.

Related papers

Product-state control in barium

Rekishu Yamazaki, Daniel S. Elliott

We report photoionization measurements that help us interpret mechanisms leading to the control of the branching ratio for resonantly enhanced, two-color, two-photon ionization experiments. We measure intermediate state populations and photoelectron angular distributions to explore the ionization dynamics. Our measurements support the interpretation that ac Stark shifts are the primary mechanism of the product state control previously observed in a similar experimental setup. We discuss the role of interference in the ionization continuum and the effect of the ac Stark shift on the product state control.

Physical Review A•Feb 15, 2006•2 citations

Observation of the Phase Lag in the Asymmetric Photoelectron Angular Distributions of Atomic Barium

Rekishu Yamazaki, Daniel S. Elliott

We have observed and measured the phase lag in the phase-dependent variation of the asymmetric photoelectron angular distribution of atomic barium. For these measurements, we photoionize the 6s6p(1)P(1) intermediate state of barium with concurrent one-photon and two-photon (omega-2omega) interactions. The laser interactions ionize the atoms in the vicinity of the series of autoionizing states converging upon the 5d(2)D(5/2) threshold. We study the variation of the phase lag as a function of the laser frequency. The variation shows strong correlation to the location of the autoionizing resonances, with full range exceeding 2pi, confirming the critical role of these resonances.

Physical Review Letters•Jan 29, 2007•30 citations

Multichannel photoelectron phase lag across atomic barium autoionizing resonances

Yimeng Wang, Chris H. Greene

Phase lag associated with coherent control where an excited system decays into more than one product channel has been subjected to numerous investigations. Although previous theoretical studies have treated the phase lag across resonances in model calculations, quantitative agreement has never been achieved between the theoretical model and an experimental measurement of the phase lag from the $\ensuremath{\omega}\ensuremath{-}2\ensuremath{\omega}$ ionization of atomic barium. Yamazaki and Elliot, Phys. Rev. Lett. 98, 053001 (2007); Phys. Rev. A 76, 053401 (2007), suggesting that a toy model with phenomenological parameters is inadequate to describe the observed phase lag behavior. Here the phase lag is treated quantitatively in a multichannel coupling formulation, and our calculation based on a multichannel quantum defect and $R$-matrix treatment achieves good agreement with the experimental observations. Our treatment also develops formulas to describe the effects of hyperfine depolarization on multiphoton ionization processes. Moreover, we identify resonances between ${\text{Ba}}^{+}\phantom{\rule{4pt}{0ex}}5{d}_{3/2}$ and $5{d}_{5/2}$ thresholds that have apparently never been experimentally observed and classified.

arXiv:2111.06547•Physical Review A•Jan 24, 2022•4 citations

Strong variation of the phase lag in the vicinity of autoionizing resonances

Rekishu Yamazaki, Daniel S. Elliott

We have observed the phase lag in the sinusoidal variation of the asymmetric photoelectron angular distributions into two ionization channels of atomic barium using an $\ensuremath{\omega}\text{\ensuremath{-}}2\ensuremath{\omega}$ excitation scheme. We excite atomic barium from the $6s6p\text{ }{^{1}P}_{1}$ intermediate state electron to an energy between the $5{d}_{3∕2}ϵ$ and the $5{d}_{5∕2}ϵ$ thresholds with concurrent one-photon and two-photon interactions. The left-right asymmetry of the photoelectron angular distributions for the two energy-resolved product states, $6{s}_{1∕2}ϵ$ and $5{d}_{3∕2}ϵ$, show sinusoidal modulation as a function of the relative phase of the $\ensuremath{\omega}\text{\ensuremath{-}}2\ensuremath{\omega}$ fields. The phase difference between these signals, or phase lag, varies rapidly with the laser frequency when the interaction is nearly resonant with autoionizing resonances in the continuum. An exceptionally large phase lag variation of over $2\ensuremath{\pi}$ was measured.

Physical Review A•Nov 5, 2007•14 citations

Experimental investigations of coherent control

Daniel S. Elliott, Ce Chen, Yi-Yian Yin +3 more

The potential of using interferences between transition amplitudes for the coherent control of photoionization rates and of asymmetric photoelectron angular distributions has been demonstrated previously. Current efforts in our laboratories are directed toward control of photoionization of NO, and on control of photoionization channels in atomic barium. This latter system is, of course, much simpler than a molecular system, and thus may provide better insight into the mechanisms involved. We will discuss our investigations of the effects of nonlinear coupling, absorption, and dispersion of the laser beams on their propagation through dense media, as observed via interference effects. Laser band structure effects and the effect of Doppler broadening will also be discussed.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jun 17, 1994•0 citations

Product State Control through Interfering Excitation Routes

Feng Wang, Ce Chen, Daniel S. Elliott

We have demonstrated control over the branching ratio for photoionization into two different continuum channels of atomic barium using an interference between two distinct photoexcitation routes. Each pathway for photoionization is a two-photon process, and is resonantly enhanced by an intermediate state. We have found the unexpected situation of destructive interference when both lasers are resonant with their respective transitions. The magnitude of the interference, as well as the exceptionally broad wavelength range over which the interference persists, is also quite surprising.

Physical Review Letters•Sep 16, 1996•47 citations
We present the results of our study on coherent control of photoionization of atomic barium. Our study focused on the understanding of the controllability, especially due to the effect of the coherent interaction between the atomic system and the laser field. The first half of the study investigates the mechanisms of the control behind the previously observed laser phase-insensitive product state control. The controllability of this excitation scheme, two-color two-photon resonantly enhanced excitation, was analyzed from two aspects, the role of ac Stark shift introduced by the strong laser field and the multi-pathway quantum mechanical interferences. We have analyzed the excitation scheme from the analysis of the photoelectron angular distribution measured using the excitation scheme and the monitoring of the intermediate state population. Analysis of the data as well as the numerical simulation showed clear understanding of the role of two mechanisms in the product state control reported. We also investigated the control of the phase lag during the product state control. We conducted the control of the phase lag in the study of asymmetric photoelectron angular distribution, which arises from the concurrent even-odd parity outgoing electron wave excitation. The phase lag was controlled in full range, 2π, and the results were analyzed in terms of the role of autoionizing resonance structures as well as the nature of outgoing electron waves at different locations of the autoionizing resonances.
We report photoionization measurements that help us interpret mechanisms leading to the control of the branching ratio for resonantly enhanced, two-color, two-photon ionization experiments. We measure intermediate state populations and photoelectron angular distributions to explore the ionization dynamics. Our measurements support the interpretation that ac Stark shifts are the primary mechanism of the product state control previously observed in a similar experimental setup. We discuss the role of interference in the ionization continuum and the effect of the ac Stark shift on the product state control.
We have observed and measured the phase lag in the phase-dependent variation of the asymmetric photoelectron angular distribution of atomic barium. For these measurements, we photoionize the 6s6p(1)P(1) intermediate state of barium with concurrent one-photon and two-photon (omega-2omega) interactions. The laser interactions ionize the atoms in the vicinity of the series of autoionizing states converging upon the 5d(2)D(5/2) threshold. We study the variation of the phase lag as a function of the laser frequency. The variation shows strong correlation to the location of the autoionizing resonances, with full range exceeding 2pi, confirming the critical role of these resonances.
Phase lag associated with coherent control where an excited system decays into more than one product channel has been subjected to numerous investigations. Although previous theoretical studies have treated the phase lag across resonances in model calculations, quantitative agreement has never been achieved between the theoretical model and an experimental measurement of the phase lag from the $\ensuremath{\omega}\ensuremath{-}2\ensuremath{\omega}$ ionization of atomic barium. Yamazaki and Elliot, Phys. Rev. Lett. 98, 053001 (2007); Phys. Rev. A 76, 053401 (2007), suggesting that a toy model with phenomenological parameters is inadequate to describe the observed phase lag behavior. Here the phase lag is treated quantitatively in a multichannel coupling formulation, and our calculation based on a multichannel quantum defect and RRR-matrix treatment achieves good agreement with the experimental observations. Our treatment also develops formulas to describe the effects of hyperfine depolarization on multiphoton ionization processes. Moreover, we identify resonances between Ba+5d3/2{\text{Ba}}^{+}\phantom{\rule{4pt}{0ex}}5{d}_{3/2}Ba+5d3/2​ and 5d5/25{d}_{5/2}5d5/2​ thresholds that have apparently never been experimentally observed and classified.
We have observed the phase lag in the sinusoidal variation of the asymmetric photoelectron angular distributions into two ionization channels of atomic barium using an $\ensuremath{\omega}\text{\ensuremath{-}}2\ensuremath{\omega}$ excitation scheme. We excite atomic barium from the 6s6p 1P16s6p\text{ }{^{1}P}_{1}6s6p 1P1​ intermediate state electron to an energy between the 5d3∕2ϵ5{d}_{3∕2}ϵ5d3∕2​ϵ and the 5d5∕2ϵ5{d}_{5∕2}ϵ5d5∕2​ϵ thresholds with concurrent one-photon and two-photon interactions. The left-right asymmetry of the photoelectron angular distributions for the two energy-resolved product states, 6s1∕2ϵ6{s}_{1∕2}ϵ6s1∕2​ϵ and 5d3∕2ϵ5{d}_{3∕2}ϵ5d3∕2​ϵ, show sinusoidal modulation as a function of the relative phase of the $\ensuremath{\omega}\text{\ensuremath{-}}2\ensuremath{\omega}$ fields. The phase difference between these signals, or phase lag, varies rapidly with the laser frequency when the interaction is nearly resonant with autoionizing resonances in the continuum. An exceptionally large phase lag variation of over $2\ensuremath{\pi}$ was measured.
The potential of using interferences between transition amplitudes for the coherent control of photoionization rates and of asymmetric photoelectron angular distributions has been demonstrated previously. Current efforts in our laboratories are directed toward control of photoionization of NO, and on control of photoionization channels in atomic barium. This latter system is, of course, much simpler than a molecular system, and thus may provide better insight into the mechanisms involved. We will discuss our investigations of the effects of nonlinear coupling, absorption, and dispersion of the laser beams on their propagation through dense media, as observed via interference effects. Laser band structure effects and the effect of Doppler broadening will also be discussed.
We have demonstrated control over the branching ratio for photoionization into two different continuum channels of atomic barium using an interference between two distinct photoexcitation routes. Each pathway for photoionization is a two-photon process, and is resonantly enhanced by an intermediate state. We have found the unexpected situation of destructive interference when both lasers are resonant with their respective transitions. The magnitude of the interference, as well as the exceptionally broad wavelength range over which the interference persists, is also quite surprising.