Article
Optics
Gan Wang, Tao-Yuan Du
Summary: The study introduces an imaginary potential to phenomenologically depict the dephasing process in solid HHG, and verifies its validity through comparison with experimental results and SBEs. Diffusion of the quantum wave packet controls the time-frequency characteristic in solid HHG, while the open-trajectory model provides consistent trajectory predictions with quantum simulations.
Article
Optics
Peter Foldi, Istvan Magashegyi, Akos Gombkoto, Sandor Varro
Summary: The optical generation of high-order harmonics is a prototypical example of nonlinear light-matter interactions in the high-field regime, where quantum optical effects have a significant influence. Understanding the dynamics of the quantized electromagnetic field during high-order harmonic generation is crucial.
Article
Physics, Multidisciplinary
Jia-Qi Liu, Xue-Bin Bian
Summary: Studying high-order harmonic generation in Fibonacci quasicrystals reveals the presence of multi-channel emissions with higher yield and broader spectral range compared to crystals, paving the way for understanding and controlling HHG in quasicrystals and potentially leading to a shorter and stronger attosecond light source based on compact solids.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Yun Zhao, Zhaoxi Chen, Cheng Wang, Yuanmu Yang, Hong-Bo Sun
Summary: In this experiment, efficient second-harmonic generation (SHG) and high-harmonic generation (HHG) were demonstrated from a LiNbO3 metasurface enhanced by guided-mode resonance. The metasurface showed high SHG efficiency and a wide range of HHG. This work may enable the development of compact coherent white-light sources in the deep ultraviolet region for spectroscopy and imaging applications.
Article
Materials Science, Multidisciplinary
Ali Kazempour, Toktam Morshedloo
Summary: In this study, the electronic response of crystalline n-doped diamond and high harmonic generation following irradiation by high-intensity laser pulses were calculated using a combination of time-dependent density functional theory and virtual crystal approximation. The results show that light doping enhances the amplitude of high harmonic generation. Additionally, doped diamond irradiated above the band gap frequency produces brighter harmonics compared to below the band gap irradiation.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Optics
Marc Jankowski, Carsten Langrock, Boris Desiatov, Marko Loncar, M. M. Fejer
Summary: We propose a new approach to supercontinuum generation and carrier-envelope-offset detection based on saturated second-order nonlinear interactions in dispersion-engineered nanowaveguides. The technique developed here broadens the interacting harmonics by forming stable bifurcations of the pulse envelopes due to an interplay between phase-mismatch and pump depletion. The scaling laws suggest that future realization based on this approach could enable supercontinuum generation with orders of magnitude less energy than current state-of-the-art devices.
Article
Multidisciplinary Sciences
Jia-Qi Wang, Yuan-Hao Yang, Ming Li, Haiqi Zhou, Xin-Biao Xu, Ji-Zhe Zhang, Chun-Hua Dong, Guang-Can Guo, C-L Zou
Summary: Nonlinear optics processes play a critical role in photonics and quantum optics for their importance in light sources and information processing. In this study, the authors successfully synthesized a high-order nonlinear process (chi((4))) by combining low-order processes in a microcavity, overcoming the limitations of materials' small intrinsic high-order susceptibility. This approach opens up new possibilities for achieving high-order optical nonlinearities and exploring functional photonic devices.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Liqiang Feng, Hang Liu
Summary: A method is presented to generate high-order single harmonics on the harmonic spectra. By properly choosing parameters and pulse characteristics, the single and double harmonics can be enhanced and generated. The results are beneficial for the generation of harmonic light sources.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
Marko Toros, Marion Cromb, Mauro Paternostro, Daniele Faccio
Summary: This article proposes an experimental scheme to probe quantum mechanics in curved spacetime using rotating Sagnac interferometers. The study shows that genuine entanglement can be generated even at low rotation frequencies.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
O. Hort, A. Dubrouil, M. A. Khokhlova, D. Descamps, S. Petit, F. Burgy, E. Mevel, E. Constant, V. V. Strelkov
Summary: A new regime of coherent XUV emission has been observed, showing potential for higher XUV intensity crucial for applications. The study explains the process of high-order parametric generation, involving the combined emission of THz and XUV photons with robust phase matching against ionization. This provides a way to use higher-energy driving pulses for generating more XUV photons.
Article
Optics
F. Rodriguez-Hernandez, F. Grossmann, Jan M. Rost
Summary: In this study, we establish and analytically derive the cutoff law for high harmonics generated with two interfering electron wave packets in the continuum. We find that the cutoff arises from the maximal action difference of the dominant classical trajectories in the phase of the time-dependent dipole response. This interference between a maximally time-delayed stranded continuum trajectory and the trajectory of a high energy continuum electron makes the continuum-continuum harmonics more sensitive to electron wave-packet dispersion compared to standard high harmonics, suggesting their prominence in dimensionally reduced systems.
Article
Mechanics
Yong Han, Ling Zhou, Ling Bai, Weidong Shi, Ramesh Agarwal
Summary: Turbulence modeling is essential for accurate prediction of turbulent fluid motion, and a new one-equation Wray-Agarwal (WA) turbulence model has been developed to improve predictions for turbulent flows with large separation and curvature. Comparison with other commonly used turbulence models shows that the WA model gives the highest accuracy in predicting the complex three-dimensional turbulent characteristics of flow with large curvature in a U-bend.
Article
Materials Science, Multidisciplinary
A. de la Torre, S. Di Matteo, D. Hsieh, M. R. Norman
Summary: SCOC is a model undoped cuprate with I4/mmm crystallographic symmetry, but recent research has shown the existence of another magnetic point group 4/mm'm' in the antiferromagnetic phase. This challenges the previous understanding of the material's symmetry and opens up new possibilities for ground states consistent with the data.
Article
Optics
Jyothsna Konkada Manattayil, Lal A. S. Krishna, Rabindra Biswas, Hyunmin Kim, Varun Raghunathan
Summary: In this study, we demonstrate sub-diffraction imaging in an infrared-sensitive third-order sum frequency generation microscope using the focal-field engineering technique. The presence of a phase mask leads to a reduction in the size of the TSFG central lobe and an improvement in contrast for periodic grating structures. Additionally, the infrared sensitivity of the focus-engineered TSFG microscope is validated through imaging of amorphous Germanium-based structures and polystyrene latex beads. The focus-engineered TSFG process shows promise as an imaging modality with infrared selectivity, improved resolution, and contrast, making it suitable for nanostructure and surface layer imaging.
Article
Optics
Yuntian Zhang, Liang Li, Jiapeng Li, Tengfei Huang, Pengfei Lan, Peixiang Lu
Summary: By solving the semiconductor Bloch equations, we investigate the orientation dependence of high-order harmonic generation in graphene, discovering different patterns for different harmonics. As the laser intensity increases, these patterns become similar, except for a double-peak structure in lower-order harmonics.
Article
Physics, Multidisciplinary
Rong Zhang, Yong-Chang Han, Shu-Lin Cong, Maksim B. Shundalau
Summary: The effect of collision energy on the magnetically tuned Li-6-Li-6 Feshbach resonance has been theoretically investigated, and the variations of other related quantities have also been discussed in detail.
Article
Chemistry, Physical
Jin-Wei Hu, Jie Yu, Yong-Chang Han
Summary: We investigated the thermal photoassociation dynamics of Mg atoms from the X-1 sigma(+)(g) state to the (1)(1)pi(g) state, or to three other higher excited states i) = (1)(1)pi(u), (2)(1)pi(u), (2)(1)sigma(+)(u). Different transition paths were formed through weak two-photon coupling, strong three-photon couplings, and one-photon couplings. The major path was found to be X-1 sigma(+)(g) +3PLANCK CONSTANT OVER TWO PI omega i)? g ? - PLANCK CONSTANT OVER TWO PI omega(1)(1)pi(g), followed by a V-type Raman transition path from |i) to (1)(1)pi(g).
CHEMICAL PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Hiroka Hasegawa, Tiffany Walmsley, Akitaka Matsuda, Toru Morishita, Lars Bojer Madsen, Frank Jensen, Oleg I. Tolstikhin, Akiyoshi Hishikawa
Summary: The dissociative ionization of tetrafluoromethane in intense laser fields has been studied, showing clear asymmetry in the spatial distribution of the produced ions. The asymmetry can be controlled by the shape of the laser pulse, and the C-F bond along the larger amplitude side tends to be broken. Theoretical analysis suggests an enhancement of tunneling ionization in the opposite direction to the observed asymmetric fragment ejection.
FRONTIERS IN CHEMISTRY
(2022)
Article
Multidisciplinary Sciences
Andrew S. Maxwell, Lars Bojer Madsen, Maciej Lewenstein
Summary: The study explores the possibility of orbital angular momentum (OAM) entanglement in attosecond imaging and investigates the entanglement properties of photoelectrons in non-sequential double ionization. Through calculations of logarithmic negativity and entanglement witness, the study reveals the robustness of entanglement to incoherence and the relationship between OAM coherence terms and entanglement measurement. The entanglement of photoelectron pairs with the highest degree of entanglement is quantified for various targets and field parameters. This methodology provides a universal approach to quantify and measure entanglement using OAM, which is well-suited for attosecond processes and can enhance imaging capabilities or generate OAM-entangled electrons.
NATURE COMMUNICATIONS
(2022)
Article
Optics
Mahmoud Abu-samha, Lars Bojer Madsen
Summary: We present theoretical results for intensity-dependent above-threshold ionization (ATI) spectra from oriented OCS molecules probed by intense femtosecond laser pulses with wavelengths of 800 and 400 nm. The calculations were performed using the time-dependent Schrodinger equation within the single-active-electron approximation and including multielectron polarization effects. The results capture some of the experimental findings, in particular when considering the sensitivity of the ATI spectra on the molecular orientation. We identify characteristic features in the ATI spectra which correspond to resonant multiphoton ionization via highly-excited Rydberg states are captured by the theory.
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
P. D. Keathley, S. V. B. Jensen, M. Yeung, M. R. Bionta, L. B. Madsen
Summary: We demonstrate the experimental feasibility of time-domain analysis of high harmonic generation (HHG) from solids with subcycle resolution and continuous spectral coverage. Using time-dependent density functional theory, we explore the insights that a time-domain, field-resolved analysis can provide about the underlying extreme nonlinear electron dynamics responsible for HHG in solids. We show that visual analysis of the time-domain fields can reveal the interplay between intra- and interband dynamical processes, providing clear insights even when spectral signatures do not. We also find that field-resolved measurements with subcycle time resolution and broad spectral coverage are essential for a comprehensive understanding of solid-state HHG.
Article
Chemistry, Physical
H. Hasegawa, A. Matsuda, T. Morishita, L. B. Madsen, F. Jensen, O. I. Tolstikhin, A. Hishikawa
Summary: Directional fragment ejection from a tetrahedral molecule CH4 under two-color laser fields has been studied. The H+ fragment, as well as the low kinetic energy components of the Coulomb explosion, preferentially ejects on the larger amplitude side of the laser electric fields. On the other hand, high energy components and the H-2(+) ion show opposite directional ejection.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Thomas Hansen, Lars Bojer Madsen
Summary: This study investigates high-harmonic generation from doped, correlated materials using the one-dimensional Hubbard model. It finds that doping has little to no effect on the dynamics and spectra for small electron-electron correlation, but has a significant impact for larger correlation. The findings are explained through a quasiparticle-based picture.
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
M. Abu-samha, Lars Bojer Madsen
Summary: This paper revisits the strong-field ionization of aligned O-2, CO2, and CS2 molecules in light of recent advances in the field of strong-field physics. By including the effect of multielectron polarization, the total ionization yields can be reduced and the alignment angle of maximum yields can shift for molecules with large polarizability.
Article
Optics
Thomas Hansen, Simon Vendelbo Bylling Jensen, Lars Bojer Madsen
Summary: Using the Hubbard model, this study investigates the effect of electron-electron correlation on high-order harmonic generation (HHG) in both finite and bulk systems. The results show that finite-size enhancement of the HHG signal is observed, attributed to electrons backscattering off the lattice edges. Furthermore, an enhancement in the high-frequency regime of the HHG spectrum is found with increasing electron-electron correlation.
Article
Optics
Lars Bojer Madsen
Summary: This study investigates the impact of nondipole effects on tunneling ionization in the limit of decreasing laser frequency. The results show the influence of the nondipole term on ionization rate, momentum, and electron dynamics, providing insights into the inclusion of nondipole effects in semiclassical models of strong-field and attosecond physics.
Article
Chemistry, Physical
H. Fujise, M. Uemura, H. Hasegawa, D. Ikeya, A. Matsuda, T. Morishita, L. B. Madsen, F. Jensen, O. Tolstikhin, A. Hishikawa
Summary: The dissociative tunneling ionization of tetrafluoromethane (CF4) in circularly polarized ultrashort intense laser fields has been studied using three-dimensional electron-ion coincidence momentum imaging. It was found that the dissociation occurs efficiently when the laser electric field points from F to C. Additionally, the results also showed a clear dependence on the polarization helicity of the laser fields.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Optics
Simon Vendelbo Bylling Jensen, Lars Bojer Madsen
Summary: Applying the semiclassical model, we have identified two connected effects in intraband high-order harmonic generation (HHG): propagation time from the point of emission to the point of detection, and beyond-electric-dipole corrections to the light-matter interaction. These effects carry information about dispersion and result in specific features in the spectra, including even-ordered harmonics in systems with space and time-inversion symmetry. They can be measured without interference from the dipole background under certain experimental geometries.
Article
Physics, Multidisciplinary
Ming-Ming Zhao, Bin-Bin Wang, Yong-Chang Han
Summary: The study revealed that the J(Pi) = 1(-) symmetry dominates the three-body recombination process in He-3 + He-3 + H- or He-3 + He-3 + D- systems. Furthermore, for a given product state, the TBR rates of the He-3 + He-3 H- system are roughly two orders of magnitude higher than that of the He-3 + He-3 + H- system, attributed to nonadiabatic couplings between entrance and recombination channels.
PHYSICAL REVIEW RESEARCH
(2022)
