Manfred Lein
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View article: Orientation-dependent ionization rate of diatomic molecules
Orientation-dependent ionization rate of diatomic molecules Open
The ionization rate of molecules in strong laser fields depends on the orientation of the ionizing electric field relative to the molecular frame. The orientation dependence of the rate plays an important role in strong-field-based attosec…
View article: Ultrafast artificial intelligence: machine learning with atomic-scale quantum systems
Ultrafast artificial intelligence: machine learning with atomic-scale quantum systems Open
We train a model atom to recognize pixel-drawn digits based on hand-written numbers in the range 0–9, employing intense light–matter interaction as a computational resource. For training, the images of the digits are converted into shaped …
View article: Convolutional neural network for retrieval of the time-dependent bond length in a molecule from photoelectron momentum distributions
Convolutional neural network for retrieval of the time-dependent bond length in a molecule from photoelectron momentum distributions Open
We apply deep learning for retrieval of the time-dependent bond length in the dissociating two-dimensional H molecule using photoelectron momentum distributions. We consider a pump-probe scheme and calculate electron momentum distrib…
View article: Convolutional neural network for retrieval of the time-dependent bond length in a molecule from photoelectron momentum distributions
Convolutional neural network for retrieval of the time-dependent bond length in a molecule from photoelectron momentum distributions Open
We apply deep learning for retrieval of the time-dependent bond length in the dissociating two-dimensional H$_2^{+}$ molecule using photoelectron momentum distributions. We consider a pump-probe scheme and calculate electron momentum distr…
View article: Mass-ratio dependent strong-field dissociation of artificial helium hydride isotopologues
Mass-ratio dependent strong-field dissociation of artificial helium hydride isotopologues Open
We study the effect of the nuclear-mass ratio in a diatomic molecular ion on the dissociation dynamics in strong infrared laser pulses. A molecular ion is a charged system, in which the dipole moment depends on the reference point and ther…
View article: Ultrafast artificial intelligence: Machine learning with atomic-scale quantum systems
Ultrafast artificial intelligence: Machine learning with atomic-scale quantum systems Open
We train a model atom to recognize hand-written digits between 0 and 9, employing intense light--matter interaction as a computational resource. For training, individual images of hand-written digits in the range 0-9 are converted into sha…
View article: Mass-ratio dependent strong-field dissociation of artificial helium hydride isotopologues
Mass-ratio dependent strong-field dissociation of artificial helium hydride isotopologues Open
We study the effect of the nuclear-mass ratio in a diatomic molecular ion on the dissociation dynamics in strong infrared laser pulses. A molecular ion is a charged system, in which the dipole moment depends on the reference point and ther…
View article: Control of Electron Wave Packets Close to the Continuum Threshold Using Near-Single-Cycle THz Waveforms
Control of Electron Wave Packets Close to the Continuum Threshold Using Near-Single-Cycle THz Waveforms Open
The control of low-energy electrons by carrier-envelope-phase-stable near-single-cycle THz pulses is demonstrated. A femtosecond laser pulse is used to create a temporally localized wave packet through multiphoton absorption at a well defi…
View article: High-order harmonic spectroscopy in an ionized high-density target
High-order harmonic spectroscopy in an ionized high-density target Open
We use high-order harmonic spectroscopy to study ionization dynamics in a macroscopic target with tunable density, spanning over six orders of magnitude. In an in situ pump-probe experiment, the target is prepared at different densities wi…
View article: Real-time propagator eigenstates
Real-time propagator eigenstates Open
Obtaining a numerical solution of the time-dependent Schrödinger equation requires an initial state for the time evolution. If the system Hamiltonian can be split into a time-independent part and a time-dependent perturbation, the initial …
View article: Revealing Coulomb time shifts in high-order harmonic generation by frequency-dependent streaking
Revealing Coulomb time shifts in high-order harmonic generation by frequency-dependent streaking Open
When an atom is ionized by a strong laser pulse, the field can drive the released electron back to the parent ion and trigger the emission of a high-order harmonic photon with a frequency that is a function of the time of ionization. The a…
View article: Deep learning for retrieval of the internuclear distance in a molecule from interference patterns in photoelectron momentum distributions
Deep learning for retrieval of the internuclear distance in a molecule from interference patterns in photoelectron momentum distributions Open
We use a convolutional neural network to retrieve the internuclear distance\nin the two-dimensional H$_2^{+}$ molecule ionized by a strong few-cycle laser\npulse based on the photoelectron momentum distribution. We show that a neural\nnetw…
View article: Nonadiabatic Strong Field Ionization of Atomic Hydrogen
Nonadiabatic Strong Field Ionization of Atomic Hydrogen Open
We present experimental data on the non-adiabatic strong field ionization of atomic hydrogen using elliptically polarized femtosecond laser pulses at a central wavelength of 390 nm. Our measured results are in very good agreement with a nu…
View article: Attoclock with bicircular laser fields as a probe of velocity-dependent tunnel-exit positions
Attoclock with bicircular laser fields as a probe of velocity-dependent tunnel-exit positions Open
Strong-field ionization of atoms can be investigated on the attosecond time scale by using the attoclock method, i.e. by observing the peak of the photoelectron momentum distribution (PMD) after applying a laser pulse with a two-dimensiona…
View article: Laser-Driven Anharmonic Oscillator: Ground-State Dissociation of the Helium Hydride Molecular Ion by Midinfrared Pulses
Laser-Driven Anharmonic Oscillator: Ground-State Dissociation of the Helium Hydride Molecular Ion by Midinfrared Pulses Open
The vibrational motion of molecules represents a fundamental example of an anharmonic oscillator. Using a prototype molecular system, HeH+, we demonstrate that appropriate laser pulses make it possible to drive the nuclear motion in the an…
View article: Electric Nondipole Effect in Strong-Field Ionization
Electric Nondipole Effect in Strong-Field Ionization Open
Strong-field ionization of atoms by circularly polarized femtosecond laser pulses produces a donut-shaped electron momentum distribution. Within the dipole approximation this distribution is symmetric with respect to the polarization plane…
View article: Theory of Subcycle Linear Momentum Transfer in Strong-Field Tunneling Ionization
Theory of Subcycle Linear Momentum Transfer in Strong-Field Tunneling Ionization Open
Interaction of a strong laser pulse with matter transfers not only energy but also linear momentum of the photons. Recent experimental advances have made it possible to detect the small amount of linear momentum delivered to the photoelect…
View article: Dissociation and ionization of HeH<sup>+</sup> in sub-cycle-controlled intense two-color fields
Dissociation and ionization of HeH<sup>+</sup> in sub-cycle-controlled intense two-color fields Open
Using quantum-mechanical, one-dimensional, non-Born–Oppenheimer simulations we study the control over the strong-field dynamics of the helium hydride molecular ion HeH + due to interaction driven by short and strong two-color laser pulses.…
View article: Probing dynamical symmetries by bicircular high-order harmonic spectroscopy beyond the Born-Oppenheimer approximation
Probing dynamical symmetries by bicircular high-order harmonic spectroscopy beyond the Born-Oppenheimer approximation Open
We explore the possibility of bicircular high-order harmonic spectroscopy to probe the laser-induced dynamics of molecules in a non-Born-Oppenheimer treatment. The numerical solutions of the time-dependent Schrodinger equation for aligned …
View article: Gouy’s Phase Anomaly in Electron Waves Produced by Strong-Field Ionization
Gouy’s Phase Anomaly in Electron Waves Produced by Strong-Field Ionization Open
Ionization of atoms by strong laser fields produces photoelectron momentum distributions that exhibit modulations due to the interference of outgoing electron trajectories. For a faithful modeling, it is essential to include previously ove…
View article: Semiclassical two-step model with quantum input: Quantum-classical approach to strong-field ionization
Semiclassical two-step model with quantum input: Quantum-classical approach to strong-field ionization Open
We present a mixed quantum-classical approach to strong-field ionization - a\nsemiclassical two-step model with quantum input. In this model the initial\nconditions for classical trajectories that simulate electron wave packet after\nioniz…
View article: Strong-field photoelectron holography beyond the electric dipole approximation: A semiclassical analysis
Strong-field photoelectron holography beyond the electric dipole approximation: A semiclassical analysis Open
Strong-field photoelectron holography denotes the interference of various\nelectron paths in laser-induced ionization of atoms, leading to interference\npatterns in the final momentum distribution. For a quantitative description of\nhologr…
View article: Reciprocal-Space-Trajectory Perspective on High-Harmonic Generation in Solids
Reciprocal-Space-Trajectory Perspective on High-Harmonic Generation in Solids Open
We revisit the mechanism of high-harmonic generation (HHG) from solids by comparing HHG in laser fields with different ellipticities but a constant maximum amplitude. It is shown that the cutoff of HHG is strongly extended in a circularly …
View article: Minimizing attosecond CEP jitter by carrier envelope phase tuning
Minimizing attosecond CEP jitter by carrier envelope phase tuning Open
Minimizing the CEP jitter of isolated attosecond pulses (IAP) will be important for future applications. This jitter is experimentally and theoretically investigated and can be minimized when the driving pulse is near its Fourier limit but…
View article: Double-slit photoelectron interference in strong-field ionization of the neon dimer
Double-slit photoelectron interference in strong-field ionization of the neon dimer Open
Wave-particle duality is an inherent peculiarity of the quantum world. The double-slit experiment has been frequently used for understanding different aspects of this fundamental concept. The occurrence of interference rests on the lack of…
View article: Direct Experimental Access to the Nonadiabatic Initial Momentum Offset upon Tunnel Ionization
Direct Experimental Access to the Nonadiabatic Initial Momentum Offset upon Tunnel Ionization Open
We report on the nonadiabatic offset of the initial electron momentum distribution in the plane of polarization upon single ionization of argon by strong field tunneling and show how to experimentally control the degree of nonadiabaticity.…
View article: Strong-field polarizability-enhanced dissociative ionization
Strong-field polarizability-enhanced dissociative ionization Open
We investigate dissociative single and double ionization of HeH+ induced by\nintense femtosecond laser pulses. By employing a semi-classical model with\nnuclear trajectories moving on field-dressed surfaces and ionization events\ntreated a…
View article: Role of the pre-acceleration in high harmonic generation from solids
Role of the pre-acceleration in high harmonic generation from solids Open
We analyze high harmonic generation (HHG) from solids in laser fields with different ellipticities but a constant maximum amplitude. It is shown that the cutoff of HHG is strongly extended in a circularly polarized field. More importantly,…
View article: Multielectron polarization effects in strong-field ionization: Narrowing of momentum distributions and imprints in interference structures
Multielectron polarization effects in strong-field ionization: Narrowing of momentum distributions and imprints in interference structures Open
We extend the semiclassical two-step model [Phys. Rev. A 94, 013415 (2016)]\nto include a multielectron polarization-induced dipole potential. Using this\nmodel we investigate the imprints of multielectron effects in the momentum\ndistribu…