Dominant-interaction Hamiltonians for high-order-harmonic generation in laser-assisted collisions

Zagoya, Carlos; Goletz, Christoph-Marian; Großmann, Frank; Rost, Jan M.

doi:10.1103/physreva.85.041401

Cited by 19 publications

(31 citation statements)

References 18 publications

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“…These oscillations, together with spatial localisation are responsible for the HHG plateau. Similar oscillations have also been identified and discussed in previous publications using TDSE computations [58] and the HK propagator [59] for cases where an initial wavepacket starts far from the core, and have been associated with the interference between different types of electron trajectories. The oscillations have also been studied in a different context, namely the adiabatic approximation [60,61] and Bohmian trajectories [62,63].…”

Section: Resultssupporting

confidence: 79%

Coupled-coherent-states approach for high-order harmonic generation

Symonds

Rontó

et al. 2015

Phys. Rev. A

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In this paper we report a version of the Coupled Coherent States (CCS) method which is able to accurately compute the HHG spectrum of an electron in a laser field in one dimension by the use of trajectory-guided grids of Gaussian wavepackets. It is shown that by periodic re-projection of the wavefunction and dynamically altering the basis set size, the method can account for a wavefunction which spreads out to cover a large area in phase space while still keeping computational expense low. The HHG spectra obtained show good agreement with those from a time dependent Schrödinger equation solver. We show also that the part of the wavefunction which is responsible for HHG moves along a periodic orbit which is far from that of classical motion. Although this paper is a proof of principle and therefore focussed on a simple one-dimensional system, future generalisations for the multi-electron case are discussed.

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Section: Resultssupporting

confidence: 79%

Coupled-coherent-states approach for high-order harmonic generation

Symonds

Rontó

et al. 2015

Phys. Rev. A

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“…Furthermore, the numerical effort in IVRs does not scale exponentially with the degrees of freedom involved (for discussions related to the CCS and HK methods applied to multidimensional systems, see [3][4][5], respectively). This efficiency may be increased by employing several strategies, such as dominant Hamiltonians in specific phase-space regions [6,7] or quantum-state reprojection [8,9]. For that reason, IVRs have been successfully used in the modeling of the short-time dynamics of quantum systems with many degrees of freedom, such as polyatomic molecules and small clusters.…”

Section: Introductionmentioning

confidence: 99%

“…Since the 1990s, there has been considerable debate about whether one may model tunneling employing semiclassical IVRs such as the HK propagator, and if so, to what extent (see [37][38][39][40][41]). To circumvent this problem, in [6,7,33] the initial electronic wave packet has been placed far away from the core. Unfortunately, these initial conditions leave out many strong-field problems, for which tunneling is expected to be the dominant ionization mechanism.…”

Section: Introductionmentioning

confidence: 99%

Quantum and semiclassical phase-space dynamics of a wave packet in strong fields using initial-value representations

Zagoya

Rontó

et al. 2014

New J. Phys.

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We assess the suitability of quantum and semiclassical initial-value representations (IVRs), exemplified by the coupled coherent states (CCS) method and the Herman-Kluk (HK) propagator, respectively, for modeling the dynamics of an electronic wave packet in a strong laser field, if this wave packet is initially bound. Using Wigner quasiprobability distributions and ensembles of classical trajectories, we identify signatures of over-the-barrier and tunnel ionization in phase space for static and time-dependent fields and the relevant sets of phasespace trajectories to model such features. Overall, we find good agreement with the full solution of the time-dependent Schrödinger equation (TDSE) for Wigner distributions constructed with both IVRs. Our results indicate that the HK propagator does not fully account for tunneling and over-the-barrier reflections. This leads to a dephasing in the time-dependent wave function, which becomes more pronounced for longer times. However, it is able to partly reproduce features associated with the wave packet crossing classically forbidden regions, although the trajectories employed in its construction always obey classical phase-space constraints. We also show that the CCS method represents a fully quantum initial value representation and accurately reproduces the results of a standard TDSE solver. Finally, we show that the HK propagator may be successfully employed to compute the time-dependent dipole acceleration and high-harmonic spectra. Nevertheless, the outcome of the semiclassical computation exhibits disagreements with the TDSE, as a consequence of the previously mentioned dephasing.

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“…For the specific case of HH, we have devised the following switching scheme (see also figure 1) which was proven by a first test [13] to yield quantitative results.…”

Section: The Concept Of Dominant Interaction Hamiltonians For High Hamentioning

confidence: 99%

“…Here, we will calculate this fraction also analytically, with the help of the so-called dominant interaction Hamiltonians (DIH). We have introduced the DIH approach in [13] with the general motivation to facilitate the computational treatment of complicated dynamics. As an example, we successfully generated numerically HH spectra with DIH.…”

Section: Introductionmentioning

confidence: 99%

An analytical approach to high harmonic generation

et al. 2012

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With the recently introduced concept of dominant interaction Hamiltonians, we construct numerically as well as analytically the spectrum of high harmonics (HH) generated in electron-ion scattering under an intense laser field. This is achieved by switching the interaction along classical electron trajectories between the integrable cases of the dipole coupled laser field or the ionic potential, depending on which potential is stronger. As a side effect, the intrinsically chaotic character of the dynamics is mapped onto the potential switching sequence while the trajectories become regular. As a consequence, only a few per cent of the trajectories needed in full semiclassical calculations are sufficient to construct the HH spectrum.

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Dominant-interaction Hamiltonians for high-order-harmonic generation in laser-assisted collisions

Cited by 19 publications

References 18 publications

Coupled-coherent-states approach for high-order harmonic generation

Coupled-coherent-states approach for high-order harmonic generation

Quantum and semiclassical phase-space dynamics of a wave packet in strong fields using initial-value representations

An analytical approach to high harmonic generation

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