Kapitza–Dirac effect with traveling waves

Spin-dependent Kapitza-Dirac scattering of electron beams from counterpropagating bichromatic laser waves in various polarization geometries is studied. The corresponding scattering probabilities are obtained by analytical and numerical solutions of the time-dependent Dirac equation, assuming a field frequency ratio of 2. When the fundamental field mode is circular-polarized, we show that spin dynamics are generally suppressed at low intensities, but can become distinct at high intensities. Conversely, when a linearly or elliptically polarized fundamental mode is combined with a second harmonic of circular polarization, strong spin effects arise already at low field intensities. In particular, a polarization configuration is identified which acts as a spin filter for free electrons.

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“…For reviews on the subject, we refer to [22,23]. Moreover, recent studies on spininsensitive KD scattering may be found in [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Controlling electron spin dynamics in bichromatic Kapitza-Dirac scattering by the laser field polarization

Dellweg

Müller

2017

Phys. Rev. A

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“…Diffraction of electrons in a standing wave of light as proposed by Kapitza and Dirac [1] has been demonstrated at the beginning of the century [2,3], with analogs by diffracting into multiple diffraction orders [4] or by using atoms [5,6]. The Kapitza-Dirac effect has already been studied theoretically, for example in adiabatic switching [7], by using perturbation theory [8][9][10], for spinless particles by using the Klein-Gordon equation [11,12], for the case of a traveling wave in a dielectric medium [13] or for a blazed, sawtooth-shaped grating [14]. See also [15] for an overview.…”

Section: Introductionmentioning

confidence: 99%

Electron-spin filter and polarizer in a standing light wave

Ahrens

2017

Phys. Rev. A

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We demonstrate the theoretical feasibility of spin-dependent diffraction and spin-polarization of an electron in two counter-propagating, circularly polarized laser beams. The spin-dynamics appears in a two-photon process of the Kapitza-Dirac effect in the Bragg regime. We show the spin-dependence of the diffraction process by comparison of the time-evolution of a spin-up and spin-down electron in a relativistic quantum simulation. We further discuss the spin properties of the scattering by studying an analytically approximated solution of the time-evolution matrix. A classification scheme in terms of unitary or non-unitary propagation matrices is used for establishing a generalized and spin-independent description of the spin properties in the diffraction process.

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“…Here only the difference with the known results is in the physical characteristic "group velocity of light" which is a rough mistake repeated also in the text, even for a monochromatic wave. As it has been shown above, diffraction effect is thoroughly the result of the phase relations and is conditioned exceptionally by the phase velocity of light that must be smaller than c. Beside this incorrectness, authors of this paper [6] ignored the existence of critical field in this process and influence of considered phenomenon of a particle "reflection" or capture on the diffraction effect, meanwhile one of these authors is also a co-author of both inelastic diffraction effect [9] and "reflection" phenomenon in the undulators [15]. Concerning the citation of considering papers devoted to diffraction effect on a travelling wave, these mechanically are included in the list of References of the paper [6] in irrelevant context by footnote: "see, for example...".…”

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confidence: 83%

“…Note that considered effect of electrons inelastic diffraction takes place at the fulfilment of classical resonance condition Eq. (6). The latter is valid if the quantum recoil of an electron because of photons absorptionradiation processes can be neglected.…”

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confidence: 99%

Electron diffraction on a traveling wave: “Inelastic Kapitza–Dirac effect”

Avetissian¹

2016

Laser Part. Beams

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In this paper conceptual points regarding electrons elastic (Kapitza-Dirac effect) and inelastic diffraction effect on the different type slowed electromagnetic wave structures/light gratings are considered. From the unified point of view it is analyzed the main works on this subject for last four decades in chronological order, pointing out the essential peculiarity inherent in induced Cherenkov, Compton, and undulator/wiggler processes too. This review article has also a goal to resolve confusion in scientific literature connected with the recently appeared paper [6] relating the electrons diffraction on a traveling wave in a dielectric medium.In recent years, especially after the realization of experiment on strongly coherent and intense laser beams [1], the interest to Kapitza-Dirac effect [2] has been increased. This, in particular, is conditioned by the significant role of observed electrons diffraction effect on highintensity laser beams-gratings [3], [1], since the diffracted from highly coherent laser gratings electron beams are coherent with each other, and Kapitza-Dirac effect is a very convenient, perhaps the best means to realize coherent electron beams (see, also, the review paper [4]). This is important fact that can serve as a basis for construction of diverse type new tools, e.g., coherent beam splitters, new type electron interferometers which would operate at rather low electron energies etc. Furthermore, since 1975 the scope of the Kapitza-Dirac effect, which is valid for the electrons elastic scattering on a standing light wave/grating, has been extended [7], [8], [9] for inelastic diffraction scattering of electrons on a slowed travelling wave propagating with the phase velocity v ph < c (c is the light speed in vacuum), to consideration of general aspects of which is devoted the present review article. The motivation of the latter have two reasons. First -that is the most important, is connected with the essential peculiarity inherent in mentioned processes (induced Cherenkov, Compton, and undulator/wiggler) [7], [8], [9] -existence of a critical field, above which a nonlinear threshold phenomenon arises radically changing the dynamics of electron-slowed travelling wave interaction, and consequently, the situation for inelastic diffraction scattering. Second, electrons diffraction effect on a travelling wave in a dielectric medium requires a special consideration because of a confusion in scientific literature connected with the appearance recently of a paper on this subject [6]. Therefore, apart from the pure scientific interest, the current review has a goal to clear up the-state-of-the-art in the considering field for last four decades in chronological order, to avoid the further confusion and misunderstandings in scientific literature.The predicted by Kapitza and Dirac in 1933 phenomenon of electrons diffraction scattering on a phase lattice of a standing light wave naturally for that time had an one-photon character because of the absence of strong and coherent radiation fields. The e...

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Kapitza–Dirac effect with traveling waves

Cited by 13 publications

References 46 publications

Controlling electron spin dynamics in bichromatic Kapitza-Dirac scattering by the laser field polarization

Controlling electron spin dynamics in bichromatic Kapitza-Dirac scattering by the laser field polarization

Electron-spin filter and polarizer in a standing light wave

Electron diffraction on a traveling wave: “Inelastic Kapitza–Dirac effect”

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