Charge-current generation in atomic systems induced by optical vortices

Köksal, Koray; Berakdar, J.

doi:10.1103/physreva.86.063812

Cited by 42 publications

(29 citation statements)

References 79 publications

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“…Because of the generalized use of EFC Hamiltonians [7,47,48], it is worth exploring further its connection to our result. To this end, let us simply postulate a general gauge transformation of the form…”

Section: Formal Derivation Of the Tl-matter Interactionmentioning

confidence: 99%

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Formulation of the twisted-light–matter interaction at the phase singularity: The twisted-light gauge

2015

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Twisted light is light carrying orbital angular momentum. The profile of such a beam is a ring-like structure with a node at the beam axis, where a phase singularity exists. Due to the strong spatial inhomogeneity the mathematical description of twisted-light-matter interaction is non-trivial, in particular close to the phase singularity, where the commonly used dipole-moment approximation cannot be applied. In this paper we show that, if the handedness of circular polarization and the orbital angular momentum of the twisted-light beam have the same sign, a Hamiltonian similar to the dipole-moment approximation can be derived. However, if the signs differ, in general the magnetic parts of the light beam become of significant importance and an interaction Hamiltonian which only accounts for electric fields is inappropriate. We discuss the consequences of these findings for twisted-light excitation of a semiconductor nanostructures, e.g., a quantum dot, placed at the phase singularity.

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Section: Formal Derivation Of the Tl-matter Interactionmentioning

confidence: 99%

“…This case has been extensively used in the literature [1,3,6,7,13,47,[56][57][58]. The vector potential in the paraxial approximation A pa (r, t) then reads…”

Section: The Vector Potential Of Twisted Lightmentioning

confidence: 99%

Formulation of the twisted-light–matter interaction at the phase singularity: The twisted-light gauge

2015

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“…For the experimental feasibility and trapping properties of LG beams we refer to [57] and others [58][59][60][61][62][63]. As the amount of transferred OAM depends strongly on the orbital location in the laser spot [55,56,[64][65][66], and the predicted time delay is explicitly related to the transferred OAM we predict a spatial resolution on orbitals having time-delay.…”

Section: Introductionmentioning

confidence: 99%

“…Each photon may transfer a quantized OAM of m OAM . Beams with more than m OAM = 300 were demonstrated offering the opportunity to access excitations way beyond the limit set by the conventional optical propensity rules [54,55] (degeneracy of involved states is also important [56]). Hence, vortices offer a new optical key to access magnetic sublevels [56] which is the starting idea of this work.…”

Section: Introductionmentioning

confidence: 99%

Discerning on a sub-optical-wavelength the attosecond time delays in electron emission from magnetic sublevels by optical vortices

Wätzel

Berakdar

2016

Phys. Rev. A

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Photoionization from energetically distinct electronic states may have a relative time delay of tens of attoseconds. Here we demonstrate that pulses of optical vortices allow measuring such attoseconds delays from magnetic sublevels, even from a spherically symmetric target. The difference in the time delay is substantial and exhibits a strong angular dependence. Furthermore, we find an atomic scale variation in the time delays depending on the target orbital position in the laser spot. The findings offer thus a qualitatively new way for a spatio-temporal sensing of the magnetic states from which the photoelectrons originate, with a spatial resolution way below the diffraction limit of the vortex beam. Our conclusions follow from analytical considerations based on symmetry, complemented and confirmed with full numerical simulations of the quantum dynamics.

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“…Many researchers have predicted that the field OAM can be transferred to the internal motion of an atom [4][5][6][7][8] or a molecule [9][10][11] in electronic dipole or quadrupole transitions, while some works [12,13] have shown that the field OAM does not interact with molecular chirality. Applications have been proposed based on direct coupling of field OAM to the internal motion [4,7,8,11,[14][15][16][17] or to the c.m. motion only [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Angular momentum transfer in interaction of Laguerre-Gaussian beams with atoms and molecules

2014

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Exchange of orbital angular momentum between Laguerre-Gaussian beam of light and center-ofmass motion of an atom or molecule is well known. We show that orbital angular momentum of light can also be transferred to the internal electronic or rotational motion of an atom or a molecule provided the internal and center-of-mass motions are coupled. However, this transfer does not happen directly to the internal motion, but via center-of-mass motion. If atoms or molecules are cooled down to recoil limit then an exchange of angular momentum between the quantized center-ofmass motion and the internal motion is possible during interaction of cold atoms or molecules with Laguerre-Gaussian beam. The orientation of the exchanged angular momentum is determined by the sign of the winding number of Laguerre-Gaussian beam. We have presented selective results of numerical calculations for the quadrupole transition rates in interaction of Laguerre-Gaussian beam with an atomic Bose-Einstein condensate to illustrate the underlying mechanism of light orbital angular momentum transfer. We discuss how the alignment of diatomic molecules will facilitate to explore the effects of light orbital angular momentum on electronic motion of molecules.

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Charge-current generation in atomic systems induced by optical vortices

Cited by 42 publications

References 79 publications

Formulation of the twisted-light–matter interaction at the phase singularity: The twisted-light gauge

Formulation of the twisted-light–matter interaction at the phase singularity: The twisted-light gauge

Discerning on a sub-optical-wavelength the attosecond time delays in electron emission from magnetic sublevels by optical vortices

Angular momentum transfer in interaction of Laguerre-Gaussian beams with atoms and molecules

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