arXiv subjects

C. Lévêque

Publications and source records attributed to C. Lévêque.

4 recordsLinked to original sources

arXiv2026

Photoelectron interferometry with spectrally shaped polychromatic infrared pulses

Laser-assisted photoelectron interferometry is a cornerstone of attosecond science, first used to characterize attosecond pulse trains and later to study photoionization dynamics. Extending this method to spectrally shaped polychromatic infrared probe fields enables encoding of information across multiple interferometric pathways within the photoelectron spectrum. Here, we experimentally demonstrate laser-assisted photoelectron interferometry using a spectrally shaped polychromatic infrared probe field composed of five distinct spectral components forming a Golomb ruler in the frequency domain. The measured interferograms exhibit multiple beating frequencies that agree with theoretical calculations, demonstrating the simultaneous encoding of multiple laser-assisted quantum beats in a single measurement. A quantitative analysis of the beating amplitudes shows that the strongly modulated temporal profile of the polychromatic probe introduces intensity- and delay-dependent distortions of the quantum beats that cannot be explained by second-order perturbation theory. These results establish the conditions required for the quantitative interpretation of polychromatic photoelectron interferometry and highlight the opportunities offered by spectro-temporal engineering of the probe field for future developments in attosecond science.

physics.atom-ph↗

arXiv2023

Production of positronium chloride: A study of the charge exchange reaction between Ps and Cl$^{-}$

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl$^-$) in the range of 10 meV - 100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl$^-$ using ab-initio methods at both mean-field and correlated levels extrapolated to the complete basis set limit. We have investigated Ps excited states up to ${n=4}$. The results suggest that the channel Ps(${n=2}$) is of particular interest for the production of PsCl in the ground state, and shows that an accurate treatment of the electronic correlation leads to a significant change in the global shape of the PsCl production cross section with respect to the mean-field level.

physics.chem-ph↗

arXiv2019

Sorting Fermionization from Crystallization in Many-Boson Wavefunctions

Fermionization is what happens to the state of strongly interacting repulsive bosons interacting with contact interactions in one spatial dimension. Crystallization is what happens for sufficiently strongly interacting repulsive bosons with dipolar interactions in one spatial dimension. Crystallization and fermionization resemble each other: in both cases -- due to their repulsion -- the bosons try to minimize their spatial overlap. We trace these two hallmark phases of strongly correlated one-dimensional bosonic systems by exploring their ground state properties using the one- and two-body density matrix. We solve the $N$-body Schrödinger equation accurately and from first principles using the multiconfigurational time-dependent Hartree for bosons (MCTDHB) and for fermions (MCTDHF) methods. Using the one- and two-body density, fermionization can be distinguished from crystallization in position space. For $N$ interacting bosons, a splitting into an $N$-fold pattern in the one-body and two-body density is a unique feature of both, fermionization and crystallization. We demonstrate that the splitting is incomplete for fermionized bosons and restricted by the confinement potential. This incomplete splitting is a consequence of the convergence of the energy in the limit of infinite repulsion and is in agreement with complementary results that we obtain for fermions using MCTDHF. For crystalline bosons, in contrast, the splitting is complete: the interaction energy is capable of overcoming the confinement potential. Our results suggest that the spreading of the density as a function of the dipolar interaction strength diverges as a power law. We describe how to distinguish fermionization from crystallization experimentally from measurements of the one- and two-body density.

cond-mat.quant-gas↗

arXiv2017

Laser-induced distortion of structural interferences in high harmonic generation

We study theoretically the two-center interferences occurring in high harmonic generation from diatomic molecules. By solving the time-dependent Schroedinger equation, either numerically or with the molecular strong-field approximation, we show that the electron dynamics results in a strong spectral smoothing of the interference, depending on the value and sign of the driving laser field at recombination. Strikingly, the associated phase-jumps are in opposite directions for the short and long trajectories. In these conditions, the harmonic emission is not simply proportional to the recombination dipole any more. This has important consequences in high harmonic spectroscopy, e.g., for accessing the molecular-frame recombination dipole in amplitude and phase.

physics.optics↗