Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2208.09812

Radiation-field-driven ionization in laser-assisted slow atomic collisions

A. Jacob, C. Müller, Alexander B Voitkiv

Published Aug 21, 2022• 0 citations
arXivHTMLPDF

Abstract

It is generally assumed that for ionization processes, which occur in slow atomic collisions, the coupling of the colliding system to the quantum radiation field is irrelevant. Here we show, however, that -- contrary to expectations -- such a coupling can strongly influence ionization of a beam of atomic species A slowly traversing a gas of atomic species B excited by a weak laser field. Moreover, this coupling becomes even more important when the collision velocity increases, getting comparable or exceeding the typical electron orbiting velocities in A and B. Our results imply furthermore that the Breit interaction can, in fact, dominate over the Coulomb interaction at very low energies.

DOI
10.48550/arxiv.2208.09812

Related papers

Dynamic two-center resonant photoionization in slow atomic collisions

Alexander B Voitkiv, C Müller, S F Zhang +1 more

Abstract An additional channel for photoionization of an atom A by an electromagnetic field opens if it interacts with an atom B resonantly coupled to this field. In this channel, which is known to be very efficient when A and B constitute a bound system, A is ionized via resonant photoexcitation of B with subsequent energy transfer to A through two-center electron correlations. We show that it can strongly dominate the ionization of A also in collisions with B, even though the average distance between A and B exceeds the typical size of a bound system by orders of magnitude.

arXiv:1809.06526•New Journal of Physics•Sep 19, 2019•8 citations

Influence of electric fields on background photo- and collisional ionization processes in Rydberg-atom collision studies

S. B. Hill, R. Parthasarathy, L. Suess +1 more

Studies of Rydberg atom collision processes, especially those with small reaction rate constants, are frequently complicated by spurious background signals associated with photoionization by thermal blackbody radiation and with ionization resulting from collisions with background gas. Here we demonstrate that the magnitude and relative importance of the signals that result from these processes are strongly influenced by the presence of an applied electric field. Possible causes of this dependence are discussed.

Physical Review A•Jun 13, 2000•2 citations

Strong-field photoionization in two-center atomic systems

Jacqueline Fedyk, Alexander B Voitkiv, Carsten Müller

Photoionization of an atom $A$ by a strong laser field in the presence of a spatially well-separated neighboring atom $B$ is considered. The laser field frequency is assumed to lie below the ionization potential of atom $A$ and be resonant with a dipole-allowed transition in atom $B$. In this situation, the ionization may occur either directly by multiphoton absorption from the laser field at the first atomic center or via an indirect pathway involving two-center electron-electron correlations, where the neighbor atom $B$ is first photoexcited and, afterwards, transfers its energy upon deexcitation radiationlessly to atom $A$. Considering monochromatic as well as bichromatic laser fields, we study various coupling regimes of the photoionization process and identify experimentally accessible parameter domains where the two-center channel is dominant.

arXiv:1807.09650•Physical Review A•Sep 27, 2018•2 citations

Resonance excitation and ionization in short-pulse laser-atom interaction

Mark Edwards

It has been widely believed that short-pulse multiphoton ionization is dominated by a resonance process: excited states of the atom are shifted by the radiation field into multiphoton resonance with the ground state, are populated, and then rapidly ionized. A recent experiment, shows significant population remaining in excited states at the end of the laser pulse, and this result has been interpreted as indicating that ionization proceeds slowly out of these states. We investigate this issue in the framework of Floquet theory, supplemented by direct numerical solution of the time-dependent Schrodinger equation. In this framework, the standard picture is portrayed as an adiabatic transition between Floquet eigenstates, which occurs as the amplitude of the laser field is ramped through the resonance value (i.e. through an avoided crossing of Floquet quasienergies). Thus it follows that the same type of transition must occur as the field is turned off. This mechanism can yield significant populations of excited states that do not suffer appreciable ionization. We exhibit this effect by numerical studies of a model atom with two bound states and two continua.

Bulletin of the American Physical Society•May 1, 1993•0 citations

Strong field ionized electron trajectories driven by squeezed light

Alex Schimmoller, Alexandra S. Landsman

Abstract In atomic strong field ionization, a photoelectron’s motion is largely determined by the laser pulse’s expected electric field, as well as the atomic potential. However, when the ionization is performed by squeezed light, the photon’s quantum statistics can modify these dynamics. In this work, we generalize the classical trajectory Monte–Carlo technique to study strong field ionization by squeezed states of light. We find that electrons driven by phase-squeezed pulses exhibit increases in longitudinal momentum consistent with what is expected from the field statistics. Meanwhile, the transverse momentum distribution shows varying influence of ‘hard’ and ‘soft’ rescattering off the Coulomb potential, and the proportion of electrons recaptured as Rydberg states decreases monotonically with the amount of squeezed light applied. This work demonstrates the added experimental control over ultrafast electron dynamics achievable by tuning light’s quantum statistics, as well as the essential role of the atomic potential in strong field ionization.

New Journal of Physics•May 14, 2026•0 citations

Photoionization of resonantly driven atomic states by an extreme ultraviolet-free-electron laser: intensity dependence and renormalization of Rabi frequencies

Benjamin Kaiser, A Brand, Martin Glässl +3 more

We analyze theoretically the high intensity photoionization dynamics of a system with two atomic states resonantly coupled by coherent extreme ultraviolet laser radiation that also gives rise to the ionization. The ground state occupation of such a system is shown to exhibit damped Rabi oscillations. The corresponding ionization, which is responsible for the damping, scales almost linearly with the field intensity when the pulse length exceeds the Rabi period. For shorter pulses a quadratic scaling is found. The Rabi frequency is shifted compared to its value for an isolated two-level system. The shift increases with excitation intensity and can acquire a high percentage of the unrenormalized frequency at high intensities. Analytical results obtained within a simplified solvable model demonstrate that the damping and the shift both result from the coupling of the discrete states to the ionization continuum and are therefore closely related. Numerical simulations for a two-electron system reveal at high intensities the importance of off-resonant ionization channels.

New Journal of Physics•Sep 12, 2013•9 citations
It is generally assumed that for ionization processes, which occur in slow atomic collisions, the coupling of the colliding system to the quantum radiation field is irrelevant. Here we show, however, that -- contrary to expectations -- such a coupling can strongly influence ionization of a beam of atomic species A slowly traversing a gas of atomic species B excited by a weak laser field. Moreover, this coupling becomes even more important when the collision velocity increases, getting comparable or exceeding the typical electron orbiting velocities in A and B. Our results imply furthermore that the Breit interaction can, in fact, dominate over the Coulomb interaction at very low energies.
Abstract An additional channel for photoionization of an atom A by an electromagnetic field opens if it interacts with an atom B resonantly coupled to this field. In this channel, which is known to be very efficient when A and B constitute a bound system, A is ionized via resonant photoexcitation of B with subsequent energy transfer to A through two-center electron correlations. We show that it can strongly dominate the ionization of A also in collisions with B, even though the average distance between A and B exceeds the typical size of a bound system by orders of magnitude.
Studies of Rydberg atom collision processes, especially those with small reaction rate constants, are frequently complicated by spurious background signals associated with photoionization by thermal blackbody radiation and with ionization resulting from collisions with background gas. Here we demonstrate that the magnitude and relative importance of the signals that result from these processes are strongly influenced by the presence of an applied electric field. Possible causes of this dependence are discussed.
Photoionization of an atom AAA by a strong laser field in the presence of a spatially well-separated neighboring atom BBB is considered. The laser field frequency is assumed to lie below the ionization potential of atom AAA and be resonant with a dipole-allowed transition in atom BBB. In this situation, the ionization may occur either directly by multiphoton absorption from the laser field at the first atomic center or via an indirect pathway involving two-center electron-electron correlations, where the neighbor atom BBB is first photoexcited and, afterwards, transfers its energy upon deexcitation radiationlessly to atom AAA. Considering monochromatic as well as bichromatic laser fields, we study various coupling regimes of the photoionization process and identify experimentally accessible parameter domains where the two-center channel is dominant.
It has been widely believed that short-pulse multiphoton ionization is dominated by a resonance process: excited states of the atom are shifted by the radiation field into multiphoton resonance with the ground state, are populated, and then rapidly ionized. A recent experiment, shows significant population remaining in excited states at the end of the laser pulse, and this result has been interpreted as indicating that ionization proceeds slowly out of these states. We investigate this issue in the framework of Floquet theory, supplemented by direct numerical solution of the time-dependent Schrodinger equation. In this framework, the standard picture is portrayed as an adiabatic transition between Floquet eigenstates, which occurs as the amplitude of the laser field is ramped through the resonance value (i.e. through an avoided crossing of Floquet quasienergies). Thus it follows that the same type of transition must occur as the field is turned off. This mechanism can yield significant populations of excited states that do not suffer appreciable ionization. We exhibit this effect by numerical studies of a model atom with two bound states and two continua.
Abstract In atomic strong field ionization, a photoelectron’s motion is largely determined by the laser pulse’s expected electric field, as well as the atomic potential. However, when the ionization is performed by squeezed light, the photon’s quantum statistics can modify these dynamics. In this work, we generalize the classical trajectory Monte–Carlo technique to study strong field ionization by squeezed states of light. We find that electrons driven by phase-squeezed pulses exhibit increases in longitudinal momentum consistent with what is expected from the field statistics. Meanwhile, the transverse momentum distribution shows varying influence of ‘hard’ and ‘soft’ rescattering off the Coulomb potential, and the proportion of electrons recaptured as Rydberg states decreases monotonically with the amount of squeezed light applied. This work demonstrates the added experimental control over ultrafast electron dynamics achievable by tuning light’s quantum statistics, as well as the essential role of the atomic potential in strong field ionization.
We analyze theoretically the high intensity photoionization dynamics of a system with two atomic states resonantly coupled by coherent extreme ultraviolet laser radiation that also gives rise to the ionization. The ground state occupation of such a system is shown to exhibit damped Rabi oscillations. The corresponding ionization, which is responsible for the damping, scales almost linearly with the field intensity when the pulse length exceeds the Rabi period. For shorter pulses a quadratic scaling is found. The Rabi frequency is shifted compared to its value for an isolated two-level system. The shift increases with excitation intensity and can acquire a high percentage of the unrenormalized frequency at high intensities. Analytical results obtained within a simplified solvable model demonstrate that the damping and the shift both result from the coupling of the discrete states to the ionization continuum and are therefore closely related. Numerical simulations for a two-electron system reveal at high intensities the importance of off-resonant ionization channels.