Article
Optics
D. Habibovic, D. B. Milosevic
Summary: This study investigates the detachment of electrons from negative ions by ultrashort few-cycle laser pulses in the near-infrared spectral region. The differential detachment probability is calculated using either numerical integration or the saddle-point method. The analysis of the photoelectron momentum distribution reveals that it depends significantly on the polarization state of the driving light and the absolute phase value. The control of the momentum distribution can be accurately achieved by manipulating the absolute phase as a control knob, particularly in regions dominated by rescattered electrons.
Article
Optics
Danish Furekh Dar, Bjoern Minneker, Stephan Fritzsche
Summary: The ionization of atoms and molecules by strong laser fields has been extensively researched both theoretically and experimentally. The strong-field approximation (SFA) accurately predicts the behavior of ionization processes in intense laser fields by analytically solving the Schrodinger equation. This paper presents an extension of the SFA that incorporates the temporal structure of few-cycle pulses, resulting in improved predictions and enhanced control over above-threshold ionization.
Article
Chemistry, Physical
Shuai Zhang, Xincheng Wang, Wenbin Jiang, Yizhu Zhang, Yuhai Jiang, Zhiyuan Zhu
Summary: The photoion-photoion coincidence (PIPICO) method is a simple and effective approach for selecting specific dissociation channels with correlated fragments in molecules. In this study, a new method called charge-encoded multi-photoion coincidence (cMUPICO) is proposed, which takes into account the charge of individual fragments and allows for clear display of coincident channels with fragments of different charge states in dissociation channels.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Shengliang Xu, Qingbin Zhang, Cheng Ran, Xiang Huang, Wei Cao, Peixiang Lu
Summary: The study measured high-resolution three-dimensional photoelectron momentum distributions of Xe atoms in a strong laser field, showing that resonant above-threshold ionization can be selectively enhanced through certain atomic Rydberg states. The self-reference ionization delay was determined by comparing the streaking angles for nonadiabatic ATI via different Rydberg states, providing a new approach to understanding ionization dynamics.
Article
Optics
Tian Sun, Lei Zhao, Yang Liu, Jing Guo, Hang Lv, Haifeng Xu
Summary: In this study, the Rydberg state excitation (RSE) process of H2 molecules induced by a strong laser field in the tunneling ionization region was investigated experimentally. Both neutral parent molecules H2 and fragment atoms H were observed to survive in high Rydberg states under the influence of strong 800-nm femtosecond laser fields, but their behaviors differed significantly with varying laser intensity and ellipticity. The results were compared with single and double ionization as well as RSE from the companion atom Ar. Analysis indicated that the H2 RSE was produced by the recapture or frustrated tunneling ionization process, and the nonsequential double ionization of H2 induced by recollision of the tunneled electrons played an important role in the fragment H RSE of H2 in strong laser fields.
Article
Chemistry, Physical
Wilhelm Becker, Dejan B. Milosevic
Summary: This study discusses the symmetries of the ionization rate and the elliptic-dichroism parameter in strong-field ionization, with a focus on high-order above-threshold ionization. By analyzing the symmetry properties of the measured momentum distribution, the ionization mechanism can be identified and information about atomic and molecular structure dynamics can be obtained.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Optics
A. S. Maxwell, A. Serafini, S. Bose, C. Figueira de Morisson Faria
Summary: The study presents a theoretical framework to optimize and understand uncertainty in laser field parameters, particularly in attoscience strong-field ionization. By deriving Fisher information in the momentum basis, it is found that both quantum and classical information scales quadratically over time. The research demonstrates that high-resolution momentum spectroscopy can significantly reduce uncertainty in in situ measurements of laser intensity, with further potential improvements using optimal quantum measurements.
Article
Physics, Multidisciplinary
Yiqi Fang, Feng-Xiao Sun, Qiongyi He, Yunquan Liu
Summary: In this study, we investigate strong-field ionization driven by quantum lights. By developing a quantum-optical-corrected strong-field approximation model, we simulate the photoelectron momentum distribution with squeezed-state light, showing distinct interference structures compared to coherent-state (classical) light. Using the saddle-point method, we analyze the electron dynamics and reveal that the photon statistics of squeezed-state light fields introduce time-varying phase uncertainty to tunneling electron wave packets and modulate the intra-cycle and inter-cycle interferences of photoelectrons. Moreover, we find that the fluctuation of quantum light significantly affects the propagation of tunneling electron wave packets, leading to considerable modifications in the ionization probability of electrons in the time domain.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Kang Lin, Sebastian Eckart, Alexander Hartung, Daniel Trabert, Kilian Fehre, Jonas Rist, Lothar Ph H. Schmidt, Markus S. Schoeffler, Till Jahnke, Maksim Kunitski, Reinhard Doerner
Summary: In the photoelectric effect, the energy of electrons is affected by their emission direction, with photoelectrons emitted against the light propagation direction shifting to higher values and those emitted along the light propagation direction shifting to lower values. This energy shift is attributed to a non-dipole contribution to the ponderomotive potential resulting from the interaction of moving electrons with incident photons.
Article
Optics
Dejan B. Milosevic, Dino Habibovic
Summary: The non-dipole effects in processes assisted by a THz field with a strength of a few MV/cm are found to be significant. The study shows that, in addition to the shift in the maximum of the photoelectron momentum distribution, the ionization probability and cutoff energy can be significantly increased.
Article
Optics
Resad Kahvedzic, Stefanie Graefe
Summary: In this paper, an analytic approach based on the strong-field approximation is proposed using the nondipole Volkov states to describe ionization and detachment in intense mid-infrared laser fields. The effects of nondipole corrections on circular and linear polarization are identified and analyzed.
Article
Physics, Fluids & Plasmas
Y. Ma, D. Seipt, A. E. Hussein, S. Hakimi, N. F. Beier, S. B. Hansen, J. Hinojosa, A. Maksimchuk, J. Nees, K. Krushelnick, A. G. R. Thomas, F. Dollar
Summary: Investigation into the effects of laser polarization and wavelength on electron injection dynamics in a laser wakefield accelerator reveals the importance of circularly polarized laser pulses in providing higher residual momentum and kinetic energy gain for ionized electrons. The strong correlation between above threshold ionization and laser wavelength highlights the complex interplay of different physical effects in laser wakefield acceleration.
PHYSICS OF PLASMAS
(2021)
Article
Optics
Lars Bojer Madsen
Summary: It has been found that above-threshold-ionization peaks disappear when the kinetic energy associated with the nondipole radiation-pressure-induced photoelectron momentum in the laser propagation direction becomes comparable to the photon energy. However, these peaks can be made to reappear if knowledge of the length and direction of the photoelectron momentum is at hand and an emission-direction-dependent momentum shift is accounted for.
Article
Optics
Dejan B. Milosevic
Summary: It has been shown that utilizing extreme terahertz (THz) pulses to assist strong-laser-field ionization can significantly increase the electron yield and emitted photoelectron energy with a lower THz field intensity. The vector potential amplitude of the THz field, comparable to that of the laser field, is the key control parameter. Numerical results are obtained using the improved strong-field approximation, and a physical explanation is provided using quantum-orbit theory.
Article
Multidisciplinary Sciences
Jiakai Li, Arash Dehzangi, Gail Brown, Manijeh Razeghi
Summary: In this work, a mid-wavelength infrared Separate Absorption and Multiplication Avalanche Photodiode (SAM-APD) with excellent performance at 200K was demonstrated, with a maximum gain of 29 which can increase to 121 as the temperature decreases. Impact ionization coefficients for electrons and holes were derived, showing a significant difference in their values. The carrier ionization ratio for the MWIR SAM-APD device was calculated to be approximately 0.097 at 200K.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
Yan-Fei Li, Yue-Yue Chen, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: This study investigates the longitudinal polarization of an electron beam during the interaction with counterpropagating circularly polarized ultraintense laser pulses, taking into account the anomalous magnetic moment of the electron. It is found that despite the suppression of helicity transfer from laser photons to the electron beam in linear and nonlinear Compton scattering processes, helicity transfer can still occur through an intermediate step of electron radiative transverse polarization, followed by spin rotation induced by the anomalous magnetic moment of the electron. Monte Carlo simulations demonstrate the consequent helicity transfer and electron radial polarization in femtosecond timescale. The findings highlight the importance of the leading QED vertex correction to the electron anomalous magnetic moment in the polarization dynamics in ultrastrong laser fields.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Xiaoxue Zhang, Erheng Wu, Henglei DU, Huicheng Guo, Chengpu Liu
Summary: The light-induced residual current in monolayer graphene driven by a circularly polarized few-cycle laser is investigated using numerical methods. It is found that an evident current direction reversal occurs when the amplitude of the driving electric field exceeds a certain threshold, which was not observed in previous studies. The internal physical mechanism for the current reversal is inter-optical-cycle interference under a suitable long laser wavelength, and the reversal-related laser field amplitude is sensitive to the ratio of ponderomotive energy to photon energy.
Article
Physics, Nuclear
Zheng Gong, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: This study investigates the plasma current filamentation of an ultrarelativistic electron beam interacting with an overdense plasma, focusing on the radiation-induced electron polarization. By using particle-in-cell simulations, three different regimes of current filaments, normal filament, abnormal filament, and quenching regimes, are classified and analyzed in detail. It is found that electron radiative polarization occurs during the azimuthal instability in momentum space, which shows significant variations across the regimes. A Hamiltonian model is proposed to explain the dynamics of electron polarization, emphasizing the role of nonlinear transverse motion of plasma filaments in inducing asymmetry in radiative spin flips and leading to an accumulation of electron polarization. This study challenges the conventional perception that quasisymmetric fields are inefficient for generating radiative spin-polarized beams, revealing the potential of electron polarization as a source of new information on laboratory and astrophysical plasma instabilities.
PHYSICAL REVIEW ACCELERATORS AND BEAMS
(2023)
Article
Physics, Multidisciplinary
M. Klaiber, Q. Z. Lv, S. Sukiasyan, D. Bakucz Canario, K. Z. Hatsagortsyan, C. H. Keitel
Summary: Recent experiments have investigated the quantum mechanically induced time delay in tunneling ionization through precise photoelectron momentum spectroscopy. Different theoretical approaches have conflicting conclusions, but a simple tunneling scenario can unequivocally identify the origin of the tunneling time delay.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Chaojin Zhang, Yi Zhang, Henglei DU, Chengpu Liu
Summary: The harmonic radiation generated by a vortex laser field and an epsilon-near-zero (ENZ) material was numerically studied using Maxwell-paradigmatic-Kerr equations. High order harmonics up to the seventh-order were produced at a low laser intensity (-109 W/cm2) for a long-duration laser field. The intensities of high order vortex harmonics at the ENZ frequency were higher than at other frequencies due to the ENZ field enhancement effects. However, for a short-duration laser field, there was an obvious frequency redshift in the high order vortex harmonic radiation due to the strong change in laser waveform propagating in the ENZ material and the non-constant field enhancement factor around the ENZ frequency.
Article
Physics, Multidisciplinary
Pei-Lun He, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: We investigate the ion momentum distribution in the x-ray-induced dissociative photoionization of molecules by analyzing the ionization under the Born-Oppenheimer approximation and simulating the ion motion using the Schrodinger equation. The entanglement between the ion and photoelectron transfers information of electronic interference to the ion dynamics, resulting in Young's double-slit interference patterns in the ion momentum distributions of dissociative molecular photoionization. We demonstrate that even when the correlated photoelectron information is lost, double-slit interference signatures still persist in the ion longitudinal momentum shift in the case of heteronuclear molecules.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Michael Klaiber, Daniel Bakucz Canario, Karen Z. Hatsagortsyan
Summary: Tunneling ionization exhibits a negative time delay due to the interference of sub-barrier recolliding and direct ionization paths. However, a Gedankenexperiment shows a positive tunneling time delay at the tunnel exit considering only the direct ionization path. This paper investigates the effects of sub-barrier recollisions on the time delay pattern at the tunnel exit and concludes that the interference decreases the delay while maintaining its positive value. The experimental findings in a modified two-color attoclock setup support the introduction of an additional time characteristic for tunneling ionization.
Article
Optics
Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: The analytical R-matrix (ARM) theory is a efficient description for the Coulomb effects of the atomic core in strong-field ionization in the nonrelativistic regime. It is generalized into the relativistic domain for the application to strong-field ionization of highly charged ions in ultrastrong laser fields. Comparison with the relativistic Coulomb-corrected strong-field approximations (SFA) is made to highlight the advantages and disadvantages. The weakly relativistic asymptotics and its accordance with the nondipole Coulomb-corrected SFA are examined. An example of a physical application, the Coulomb enhancement of tunneling ionization probability for highly charged ions at the cutoff of the direct channel, is discussed.
Article
Astronomy & Astrophysics
Kai -Hong Zhuang, Yue-Yue Chen, Yan-Fei Li, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: Polarized leptons can be generated through breaking the symmetry of the interaction process between an ultrarelativistic electron beam and an ultraintense laser pulse. The polarization is related to the emission angle and can be used to produce high-density electron and positron jets.
Article
Multidisciplinary Sciences
Kun Xue, Ren-Tong Guo, Feng Wan, Rashid Shaisultanov, Yue-Yue Chen, Zhong-Feng Xu, Xue-Guang Ren, Karen Z. Hatsagortsyan, Christoph H. Keitel, Jian-Xing Li
Summary: Generation of arbitrarily spin-polarized electron and positron beams has been investigated through the interaction between high-energy polarized gamma-photons and ultraintense asymmetric laser pulses. A semi-classical Monte Carlo method is developed to describe the pair creation and polarization. Control over the polarization of the created electrons and positrons is achieved by manipulating the polarization of the parent gamma-photons and the driving laser field. Dense GeV lepton beams with high polarization degree can be obtained using this all-optical method, which has potential applications in exploring physics beyond the Standard Model.
FUNDAMENTAL RESEARCH
(2022)
Article
Astronomy & Astrophysics
Yue-Yue Chen, Karen Z. Hatsagortsyan, Christoph H. Keitel, Rashid Shaisultanov
Summary: This paper provides a derivation of fully polarization-resolved probabilities for high-energy photon emission and electron-positron pair production in ultrastrong laser fields. The author emphasizes the significance of these probabilities in studying polarization effects in nonlinear QED processes.
Article
Optics
M. Klaiber, Q. Z. Lv, K. Z. Hatsagortsyan, C. H. Keitel
Summary: This study investigates the tunneling ionization of an atom in ultrashort laser pulses. The researchers found that when the driving laser pulse is switched on or off, the photoelectron momentum distribution displays an edge effect due to diffraction. The study highlights the importance of considering nonadiabatic dynamical features and proposes an efficient method to remove the edge effect in the photoelectron momentum distribution.
Article
Optics
Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: The electron nondipole dynamics in tunneling ionization in an elliptically polarized laser field is studied using a relativistic Coulomb-corrected strong-field approximation. Attoclock angle-resolved light-front momentum distributions are calculated at different ellipticities of the laser field and analyzed with an improved simple model. The correlations between longitudinal and transverse momentum components are examined.
Article
Physics, Multidisciplinary
Zheng Gong, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: This study proposes a new method for probing the dynamics of ultrarelativistic plasma using polarization properties of emitted gamma-photons. The results demonstrate that the polarization signal of gamma-photons can provide valuable information for the research fields of laser-driven plasma, accelerator science, and laboratory astrophysics.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Optics
Pei-Lun He, Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel
Summary: This study investigates the nondipole under-the-barrier dynamics of electron during strong-field tunneling ionization and examines the role of the Coulomb field of the atomic core. The research demonstrates that the sub-barrier Coulomb field increases the photoelectron nondipole momentum shift along the laser propagation direction.
