Christoph H. Keitel

Nondipole Coulomb effects in strong x-ray field ionization

Haoyuan He, Karen Z. Hatsagortsyan, Christoph H. Keitel

Atomic ionization in superintense x-ray fields is studied through numerical solutions of the time-dependent Schrödinger equation including nondipole corrections. The role of the Coulomb potential of the atomic core in the nondipole regime is analyzed for a linearly polarized laser field. In …

Quasiperiodic nondipole ionization dynamics in the x-ray stabilization regime

Anonymous, Karen Z. Hatsagortsyan, Christoph H. Keitel

Recent advances in strong x-ray laser techniques enable the study of nonlinear multiphoton ionization in extreme high-frequency fields. Although the stabilization regime in such fields is theoretically established, its modified properties in the nondipole regime for long laser pulses remains unknown. Here …

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Bright isolated light pulses reaching 18 attoseconds from high-order harmonic generation by post-compressed Yb lasers

Jingsong Gao, Mahmudul Hasan, Hao Liang, Ziyang Guo et autres

Generating ever-shorter and brighter light pulses is a central goal of ultrafast science, enabling coherent control and observation of electron dynamics on their natural timescale. State-of-the-art isolated attosecond pulse generation currently achieves pulse durations of 40-50 attoseconds. Here we demonstrate isolated attosecond …

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QED corrections in unstable vacuum

V. A. Zaytsev, Vladimir A. Yerokhin, Christoph H. Keitel, Natalia S. Oreshkina

Self-energy and vacuum polarization effects in quantum electrodynamics (QED) are calculated for the supercritical Coulomb field, where Dirac energy levels become embedded in the negative-energy continuum. In this regime, the quantum vacuum becomes unstable, resulting in spontaneous electron-positron pair creation. By calculating …

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Intrinsic nonlocality of spin- and polarization-resolved probabilities in strong-field quantum electrodynamics

Anonymous, A. Di Piazza, T. Podszus, Christoph H. Keitel et autres

Spin and polarization are central to precision tests of fundamental physics and for interpreting radiation from astrophysical sources and ultraintense laser-matter experiments. Here, focusing on the fundamental process of nonlinear Compton scattering, we demonstrate that a key assumption underlying current strong-field quantum …

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Radiation-induced electron spin polarization in ultrarelativistic kinetic turbulence

Peng Liu (120506), Karen Z. Hatsagortsyan, Christoph H. Keitel, Zheng Gong

Electron spin polarization in radiative plasmas with ultrarelativistic kinetic turbulence under highly magnetized conditions is investigated using particle-in-cell simulations. We observe that a significant spin polarization can be sustained when the leptons undergo energetic photon emission accompanied by spin flips during the …

Superradiant Parametric Mössbauer Radiation Source

Ze-an Peng, Christoph H. Keitel, Jörg Evers

Future applications of the spectrally narrow x-ray resonances in Mössbauer nuclei require x-ray sources with exceptionally high peak and average spectral flux. Here, we introduce a superradiant parametric Mössbauer radiation (SPMR) source, which utilizes the scattering of spatially microstructured electron bunches produced …

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Parametric Mössbauer radiation in the grazing-diffraction geometry: Specular diffraction and superradiant amplification

Ze-an Peng, Christoph H. Keitel, Jörg Evers

Parametric x-ray radiation (PXR) is a tunable and versatile x-ray production mechanism that relies on relativistic electrons traversing through a crystal. When the crystal contains Mössbauer nuclei, they may also contribute to the x-ray generation, giving rise to spectrally narrow parametric Mössbauer …

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Strong-field focusing of high-energy particles in beam-multifoil collisions

Aimé Matheron, Doug Storey, M. Gilljohann, Sheldon Rego et autres

Extreme beams of charged particles and photons, reaching ultrahigh densities or producing intense gamma-ray bursts, are central to accelerator physics, laboratory astrophysics, and strong-field quantum electrodynamics research. Yet their generation is hindered by conventional focusing methods at multi-GeV energies that rely on …

Intrinsic Nonlocality of Spin- and Polarization-Resolved Probabilities in Strong-Field Quantum Electrodynamics

Samuele Montefiori, A. Di Piazza, T. Podszus, Christoph H. Keitel et autres

Spin and polarization are central to precision tests of fundamental physics and for interpreting radiation from astrophysical sources and ultraintense laser-matter experiments. Here, focusing on the fundamental process of nonlinear Compton scattering, we demonstrate that a key assumption underlying current strong-field quantum …

Role of quantum dynamics in coherent and incoherent radiation during tunneling ionization

Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel

Radiation during strong-field tunneling ionization is investigated. The spontaneous as well as the coherent components of the radiation are calculated describing the ionization dynamics via the strong-field approximation, and the role of the quantum dynamics at tunneling is analyzed. The competition between …

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Quasiperiodic nondipole ionization dynamics in the x-ray stabilization regime

Aleksandr V. Boitsov, Karen Z. Hatsagortsyan, Christoph H. Keitel

Recent advances in strong x-ray laser techniques enable the study of nonlinear multiphoton ionization in extreme high-frequency fields. Although the stabilization regime in such fields is theoretically established, its modified properties in the nondipole regime for long laser pulses remains unknown. Here, …