Dichotomy of the Hydrogen Atom in Superintense, High-Frequency Laser Fields

Walet, Niels R.; Gavrila, M.; McCurdy, C. William

doi:10.1103/physrevlett.61.939

Cited by 327 publications

(154 citation statements)

References 9 publications

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“…Many aspects of this phenomenon can be understood by performing a Kramers-Henneberger (KH) transformation to the rest frame of a classical electron in the laser field. In particular, by developing a highfrequency Floquet theory in the KH frame [2], stabilization can be seen to have its origin in the rapid quiver motion of the atomic electron in the laser field. This allows the electron dynamics to be described by an effective potential that, on average, localizes the electron away from the vicinity of the nucleus.…”

Section: (Received 13 April 2000)mentioning

confidence: 99%

Breakdown of Stabilization of Atoms Interacting with Intense, High-Frequency Laser Pulses

et al. 2000

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An analysis of the influence of the magnetic field of an intense, high-frequency laser pulse on the stabilization of an atomic system is presented. We demonstrate that at relatively modest intensities the magnetic field can significantly alter the dynamics of the system. In particular, a breakdown of stabilization occurs, thereby restricting the intensity regime in which the atom is relatively stable against ionization. Counterpropagating pulses do not negate the detrimental effects of the magnetic field. We compare our quantum mechanical results with classical Monte Carlo simulations. PACS numbers: 32.80.Fb, 32.80.Rm, 42.50.Hz Theoretical studies of atoms interacting with highfrequency intense laser pulses have predicted a significant decrease in the ionization probability with increasing laser intensity. This phenomenon is referred to as atomic stabilization, and has been extensively studied over the past decade [1]. Many aspects of this phenomenon can be understood by performing a Kramers-Henneberger (KH) transformation to the rest frame of a classical electron in the laser field. In particular, by developing a highfrequency Floquet theory in the KH frame [2], stabilization can be seen to have its origin in the rapid quiver motion of the atomic electron in the laser field. This allows the electron dynamics to be described by an effective potential that, on average, localizes the electron away from the vicinity of the nucleus. Subsequent ab initio Floquet calculations confirmed that ionization rates decrease with increasing intensity in a high-frequency field [3]. By directly integrating the time-dependent Schrödinger equation numerically, simulations in one [4] and three dimensions [5] demonstrated reductions in the ionization probability with increasing laser intensity when an atom interacts with realistic laser pulses having a finite duration. Further work has been carried out in order to elucidate the effects of the pulse shape and duration [6,7]. We also note that evidence of atomic stabilization of Rydberg states has been observed experimentally [8].In the above-mentioned theoretical studies, the magnetic component of the laser pulse was neglected. However, as the laser intensity increases, relativistic effects that alter the stabilization dynamics become important. Classical Monte Carlo simulations have indicated that the magnetic field pushes the electron in the laser pulse propagation direction, reducing the degree of stabilization [9]. Relativistic wave equations have also been considered within the context of reduced dimensional models [10,11]. However, it is also of interest to study the effects that are neglected in the dipole approximation by using the fully space-and time-dependent vector potential in the nonrelativistic Schrödinger equation [12]. For atomic hydrogen, this results in the cylindrical symmetry of the system being broken, thereby requiring a fully three-dimensional calculation to be carried out for extremely high laser intensities. This is a computationally demanding task. Howev...

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Section: (Received 13 April 2000)mentioning

confidence: 99%

Breakdown of Stabilization of Atoms Interacting with Intense, High-Frequency Laser Pulses

et al. 2000

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“…From perturbation theory calculations, a general increase in breakup probability with intensity of the imposed radiation field is expected. It therefore came as a big surprise to many when, more than 20 years ago, theoretical studies of atomic hydrogen in ultraintense, high-frequency laser fields showed some evidence of the complete opposite scenario, i.e., that the atom may eventually become more stable as the ionizing radiation gets stronger [3][4][5][6][7][8][9][10][11]. This rather counterintuitive phenomenon, called atomic stabilization, has since then been studied extensively; see, e.g., [12][13][14][15] and references therein.…”

Section: Introductionmentioning

confidence: 99%

Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

et al. 2011

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The ionization dynamics of circular Rydberg states in strong circularly polarized infrared (800 nm) laser fields is studied by means of numerical simulations with the time-dependent Schrödinger equation. We find that at certain intensities, related to the radius of the Rydberg states, atomic stabilization sets in, and the ionization probability decreases as the intensity is further increased. Moreover, there is a strong dependence of the ionization probability on the rotational direction of the applied laser field, which can be understood from a simple classical analogy.

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“…From these the total overlap matrix is found for every angular momentum component by taking the Kronecker product S = I k ⊗ S 1 ⊗ S 2 , where I k denotes the identity matrix and k is the angular index. The resulting TDSE may then be written as iS ∂ ∂t c(t) = H(t)c(t) ( 6 ) in matrix form. We solve the TDSE using a scheme based on the first-order approximation to the matrix exponential…”

Section: A Ab Initio Calculationsmentioning

confidence: 99%

“…More than 20 years ago, theoretical studies of atomic hydrogen in ultraintense, high-frequency laser fields produced an unexpected result [1][2][3][4][5][6][7][8][9]: When increasing the intensity of the laser pulse to such a degree that the applied forces dominate over the Coulomb attraction between the nucleus and the electron, the ionization probability does not increase accordingly but rather stabilizes or starts subsiding. This counterintuitive phenomenon was dubbed atomic stabilization and was subject to much research in the following decade.…”

Section: Introductionmentioning

confidence: 99%

Multiphoton ionization and stabilization of helium in superintense xuv fields

et al. 2011

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Multiphoton ionization of helium is investigated in the superintense field regime, with particular emphasis on the role of the electron-electron interaction in the ionization and stabilization dynamics. To accomplish this, we solve ab initio the time-dependent Schrödinger equation with the full electron-electron interaction included. By comparing the ionization yields obtained from the full calculations with the corresponding results of an independent-electron model, we come to the somewhat counterintuitive conclusion that the single-particle picture breaks down at superstrong field strengths. We explain this finding from the perspective of the so-called Kramers-Henneberger frame, the reference frame of a free (classical) electron moving in the field. The breakdown is tied to the fact that shake-up and shake-off processes cannot be properly accounted for in commonly used independent-electron models. In addition, we see evidence of a change from the multiphoton to the shake-off ionization regime in the energy distributions of the electrons. From the angular distribution, it is apparent that the correlation is an important factor even in this regime.

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Dichotomy of the Hydrogen Atom in Superintense, High-Frequency Laser Fields

Cited by 327 publications

References 9 publications

Breakdown of Stabilization of Atoms Interacting with Intense, High-Frequency Laser Pulses

Breakdown of Stabilization of Atoms Interacting with Intense, High-Frequency Laser Pulses

Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

Multiphoton ionization and stabilization of helium in superintense xuv fields

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