Quantum Effects in Double Ionization of Argon below the Threshold Intensity

Hao, Xiaolei; Chen, Jing; Li, Weidong; Wang, Bingbing; Wang, Xiaodong; Becker, W.

doi:10.1103/physrevlett.112.073002

Cited by 88 publications

(66 citation statements)

References 22 publications

(27 reference statements)

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“…If quantum interference is absent, the SFA retains fourfold symmetry for RESI distributions, in agreement with rigorous momentum constrains [15]. Recently, however, SFA computations have shown that this symmetry can be broken, if the interference stemming from different excitation channels is incorporated [20]. Therein, it has been argued that inter-channel interference is paramount for obtaining anti-correlated RESI distributions.In this Letter, we show that one may obtain correlated, anti-correlated, cross-or ring-shaped RESI distributions in an SFA computation, by choosing appropriate coherent superpositions of excitation channels.…”

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confidence: 66%

Controlling Below-Threshold Nonsequential Double Ionization via Quantum Interference

Maxwell

Faria

2016

Phys. Rev. Lett.

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We show through simulation that quantum interference in nonsequential double ionization can be used to control the recollision excitation with subsequent ionization (RESI) mechanism. This includes the shape, localization, and symmetry of RESI electron-momentum distributions, which may be shifted from a correlated to an anticorrelated distribution or vice versa, far below the direct ionization threshold intensity. As a testing ground, we reproduce recent experimental results by employing specific coherent superpositions of excitation channels. We examine two types of interference, from electron indistinguishability and intracycle events, and from different excitation channels. These effects survive focal averaging and transverse-momentum integration. DOI: 10.1103/PhysRevLett.116.143001 Correlation and anticorrelation have been extensively studied in strong-field, laser-induced nonsequential double ionization (NSDI). Particularly with the Cold Target Recoil Ion Momentum Spectroscopy technique, information about the electron momenta has become experimentally accessible since the early 2000s. Several features in these distributions provide information about the type of interaction by which NSDI occurs, and the physical mechanisms behind it. It is commonly accepted that NSDI results from the laserinduced inelastic recollision of an electron with its parent ion [1]. If the driving-field intensity is high enough, upon recollision the first active electron releases a second electron by electron-impact (EI) ionization. In contrast, for the socalled below-threshold intensities, the kinetic energy transferred from the first electron to the core is not sufficient to free the second electron. Instead, the recolliding electron imparts only enough energy that the second electron is excited and then ionized with a time delay. This mechanism is known as recollision excitation with subsequent ionization (RESI).Over the years, the prevalent view has been that, in EI, the two electrons will exhibit correlated momenta as a consequence of their being released simultaneously. In contrast, for RESI, back-to-back emission will occur due to the time delay between recollision of the first electron and ionization of the second electron. This view has been backed using classical models, which have reproduced many of the key features encountered in experiments (for reviews, see Ref.[2]). Such models also exhibit excellent agreement with the outcome of other methods, such as the full solution of the time-dependent Schrödinger equation [3] and the strong-field approximation (SFA) [4-6]. The abovementioned studies, performed for EI, suggested that quantum mechanical features such as interference will not survive integration over momentum components perpendicular to the laser-field polarization and focal averaging, which is the typical scenario in NSDI experiments. These conclusions were then extrapolated to RESI without much evidence.Classical models have also successfully reproduced the anticorrelated behavior observed in early RESI experim...

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confidence: 66%

Controlling Below-Threshold Nonsequential Double Ionization via Quantum Interference

Maxwell

Faria

2016

Phys. Rev. Lett.

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“…(22) is associated with the continuum propagation. When the integrand remains an analytic function everywhere in the complex time plane except the infinity, as is the case for the Coulomb-free action (7), the integration contour connecting t s and t d can be chosen arbitrarily. This makes, in particular, the value of tunnel exit ill-defined for theories where the Coulomb field is fully discarded [18,48].…”

Section: Choice Of Contours and Regularizationmentioning

confidence: 99%

“…Quantum interference is not only vital for photoelectron holography, but plays an important role in molecular imaging [4] and in the study of other phenomena. Examples are high-order harmonic generation (HHG) [5], and, possibly, laser-induced nonsequential double ionization (NSDI) [6][7][8][9]. Besides this, different interpretations of the ionization process, in terms of paths, appeared pivotal for verification of such theoretical concepts as the tunnel exit, the tunneling time and the attoclock setup [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Treating branch cuts in quantum trajectory models for photoelectron holography

2018

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Most implementations of Coulomb-distorted strong-field approaches that contain features such as tunneling and quantum interference use real trajectories in continuum propagation, while a fully consistent approach must use complex trajectories throughout. A key difficulty in the latter case are branch cuts that appear due to the specific form of the Coulomb potential. We present a method for treating branch cuts in quantum-trajectory models, which is subsequently applied to photoelectron holography. Our method is not numerically intensive, as it does not require finding the location of all branching points and branch cuts prior to its implementation, and is applicable to Coulomb-free and Coulomb-distorted trajectories. We show that the presence of branch cuts leads to discontinuities and caustics in the holographic fringes in above-threshold ionization (ATI) photoelectron angular distributions (PAD). These artefacts are removed applying our method, provided they appear far enough from the polarization axis. A comparison with the full solution of the time-dependent Schrödinger equation is also performed, and a discussion of the applicability range of the present approach is provided.

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“…Additionally to the interference effects studied above, the prefactors (4) and (5) will introduce a momentum bias, which influences the shapes and, in principle, the quantum interference between events or channels. In the specific problem addressed in [32], the target chosen is Argon, whose first and second ionization potentials are E 1g = 0.58 a.u. and E 2g = 1.02 a.u., respectively.…”

Section: The Effect Of the Prefactorsmentioning

confidence: 99%

“…One should note, however, that in none of the SFA computations has interference between different events or excitation channels been incorporated. Recently, however, SFA computations using inter-channel interference have shown that the fourfold symmetry can be broken [32]. Indeed, it has been argued that quantum interference is paramount, and that it may lead to anti-correlated distributions.…”

Section: Introductionmentioning

confidence: 99%

Quantum interference in time-delayed nonsequential double ionization

Maxwell

Faria

2015

Phys. Rev. A

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We perform a systematic analysis of quantum interference in nonsequential double ionization focusing on the recollision-excitation with subsequent ionization (RESI) mechanism, employing the strong-field approximation (SFA). We find that interference has a major influence on the shape, localization and symmetry of the correlated electron momentum distributions. In particular, the fourfold symmetry with regard to the parallel momentum components observed in previous SFA studies is broken. Two types of interference are observed and thoroughly analyzed, namely that caused by electron indistinguishability and intra-cycle events, and that stemming from different excitation channels. We find that interference is most prominent around the diagonal and anti-diagonal in the parallel-momentum plane and provide fully analytical expressions for most interference patterns encountered. We also show that this interference can be controlled by an appropriate choice of phase and excited-state geometry. This leads a to myriad of shapes for the RESI distributions including correlated, anti-correlated and ring-shaped.

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Quantum Effects in Double Ionization of Argon below the Threshold Intensity

Cited by 88 publications

References 22 publications

Controlling Below-Threshold Nonsequential Double Ionization via Quantum Interference

Controlling Below-Threshold Nonsequential Double Ionization via Quantum Interference

Treating branch cuts in quantum trajectory models for photoelectron holography

Quantum interference in time-delayed nonsequential double ionization

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