Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities

Abstract Thirty years ago, Coullet et al. proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex. Since then, optical vortices have been widely studied, inspired by the hydrodynamics sharing similar mathematics. Akin to a fluid vortex with a central flow singularity, an optical vortex beam has a phase singularity with a certain topological charge, giving rise to a hollow intensity distribution. Such a beam with helical phase fronts and orbital angular momentum reveals a subtle connection between macroscopic physical optics and microscopic quantum optics. These amazing properties provide a new understanding of a wide range of optical and physical phenomena, including twisting photons, spin–orbital interactions, Bose–Einstein condensates, etc., while the associated technologies for manipulating optical vortices have become increasingly tunable and flexible. Hitherto, owing to these salient properties and optical manipulation technologies, tunable vortex beams have engendered tremendous advanced applications such as optical tweezers, high-order quantum entanglement, and nonlinear optics. This article reviews the recent progress in tunable vortex technologies along with their advanced applications.

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Extending the Applicability of the ANI Deep Learning Molecular Potential to Sulfur and Halogens

10.26434/chemrxiv.11819268.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Christian Devereux ◽

Justin Smith ◽

Kate Davis ◽

Kipton Barros ◽

Roman Zubatyuk ◽

...

Keyword(s):

Drug Development ◽

Autonomous Vehicles ◽

Potential Energy Surfaces ◽

Organic Molecules ◽

Chemical Elements ◽

Molecular Potential ◽

Wide Range ◽

Energy Surfaces ◽

New Applications ◽

Physical Phenomena

<p>Machine learning (ML) methods have become powerful, predictive tools in a wide range of applications, such as facial recognition and autonomous vehicles. In the sciences, computational chemists and physicists have been using ML for the prediction of physical phenomena, such as atomistic potential energy surfaces and reaction pathways. Transferable ML potentials, such as ANI-1x, have been developed with the goal of accurately simulating organic molecules containing the chemical elements H, C, N, and O. Here we provide an extension of the ANI-1x model. The new model, dubbed ANI-2x, is trained to three additional chemical elements: S, F, and Cl. Additionally, ANI-2x underwent torsional refinement training to better predict molecular torsion profiles. These new features open a wide range of new applications within organic chemistry and drug development. These seven elements (H, C, N, O, F, Cl, S) make up ~90% of drug like molecules. To show that these additions do not sacrifice accuracy, we have tested this model across a range of organic molecules and applications, including the COMP6 benchmark, dihedral rotations, conformer scoring, and non-bonded interactions. ANI-2x is shown to accurately predict molecular energies compared to DFT with a ~10<sup>6</sup> factor speedup and a negligible slowdown compared to ANI-1x. The resulting model is a valuable tool for drug development that can potentially replace both quantum calculations and classical force fields for myriad applications.</p>

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Sectorial perturbation of vortex beams: Shannon entropy, orbital angular momentum and topological charge

Computer Optics ◽

10.18287/2412-6179-2019-43-5-723-734 ◽

2019 ◽

Vol 43 (5) ◽

pp. 723-734 ◽

Cited By ~ 6

Author(s):

A.V. Volyar ◽

M.V. Bretsko ◽

Ya.E. Akimova ◽

Yu.A. Egorov ◽

V.V. Milyukov

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Shannon Entropy ◽

Topological Charge ◽

External Perturbation ◽

Informational Entropy ◽

Large Perturbation ◽

Wide Range ◽

Vortex Beams ◽

Computing Measuring

Transformations of the vortex beams structure subjected to sectorial perturbation were theoretically and experimentally studied. The analysis was based on computing (measuring) the vortex spectrum that enables us to find the orbital angular momentum (OAM) and Shannon entropy (informational entropy). We have revealed that, in the general case, the number of vortices caused by an external perturbation is not related to the topological charge. For arbitrary perturbation, the topological charge remains equal to the initial topological charge of the unperturbed vortex beam. Growth of the vortex number induced by perturbations is associated with the optical uncertainty principle between the sectorial angle and the OAM. The computer simulation has shown that OAM does not depend on the number of vortices induced by perturbations. Moreover, two maxima are formed both in the positive and negative regions of the vortex spectrum. As a result, the OAM does not practically change in a wide range of perturbation angles from 0 to 90 °. However, at large perturbation angles, when the energy is almost equally redistributed between the vortex modes with opposite signs of the topological charge, the OAM rapidly decreases. At the same time, the Shannon entropy monotonically increases with growing perturbation angle. This is due to the fact that the entropy depends only on the number of vortex states caused by external perturbations.

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Stem–loop formation drives RNA folding in mechanical unzipping experiments

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2025575119 ◽

2022 ◽

Vol 119 (3) ◽

pp. e2025575119

Author(s):

Paolo Rissone ◽

Cristiano V. Bizarro ◽

Felix Ritort

Keyword(s):

Optical Tweezers ◽

Rna Structure ◽

Nearest Neighbor ◽

Rna Folding ◽

General Mechanism ◽

Loop Formation ◽

Stem Loop ◽

Wide Range ◽

Irreversible Effects ◽

And Function

Accurate knowledge of RNA hybridization is essential for understanding RNA structure and function. Here we mechanically unzip and rezip a 2-kbp RNA hairpin and derive the 10 nearest-neighbor base pair (NNBP) RNA free energies in sodium and magnesium with 0.1 kcal/mol precision using optical tweezers. Notably, force–distance curves (FDCs) exhibit strong irreversible effects with hysteresis and several intermediates, precluding the extraction of the NNBP energies with currently available methods. The combination of a suitable RNA synthesis with a tailored pulling protocol allowed us to obtain the fully reversible FDCs necessary to derive the NNBP energies. We demonstrate the equivalence of sodium and magnesium free-energy salt corrections at the level of individual NNBP. To characterize the irreversibility of the unzipping–rezipping process, we introduce a barrier energy landscape of the stem–loop structures forming along the complementary strands, which compete against the formation of the native hairpin. This landscape correlates with the hysteresis observed along the FDCs. RNA sequence analysis shows that base stacking and base pairing stabilize the stem–loops that kinetically trap the long-lived intermediates observed in the FDC. Stem–loops formation appears as a general mechanism to explain a wide range of behaviors observed in RNA folding.

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Vortices Nucleation By Inherent Fluctuations In Nematic Liquid Crystal Cells

10.21203/rs.3.rs-859280/v1 ◽

2021 ◽

Author(s):

Esteban Aguilera ◽

Marcel G. Clerc ◽

Valeska Zambra

Keyword(s):

Liquid Crystal ◽

Optical Tweezers ◽

Nematic Liquid Crystal ◽

Topological Defects ◽

Optical Vortices ◽

Topological Features ◽

Nucleation Mechanisms ◽

Multistable Systems ◽

Light Beams ◽

Crystal Cells

Abstract Multistable systems are characterized by exhibiting domain coexistence, where each domain accounts for the different states. In the case of these systems are described by vectorial fields, domains are connected through topological defects. Vortices are one of the most frequent and studied topological defect points. Optical vortices are equally relevant for their fundamental features as beams with topological features and their applications in image processing, telecommunications, optical tweezers, and quantum information. The interaction of light beams with matter vortices in liquid crystal cells is a natural source of optical vortices. The rhythms that govern the emergence of matter vortexes due to fluctuations are not established. Here we investigate the nucleation mechanisms of the matter vortices in liquid crystal cells and establish statistical laws that govern them. Based on a stochastic amplitude equation, the law for the number of nucleated vortices as a function of anisotropy, voltage, and noise level intensity is set. Experimental observations in a nematic liquid crystal cell with homeotropic anchoring and a negative anisotropic dielectric constant under the influence of a transversal electric field show a fair agreement with the theoretical findings.

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Anomalously localized states and multifractal correlations of critical wave functions in two-dimensional electron systems with spin-orbital interactions

Physical Review B ◽

10.1103/physrevb.69.125301 ◽

2004 ◽

Vol 69 (12) ◽

Cited By ~ 12

Author(s):

H. Obuse ◽

K. Yakubo

Keyword(s):

Wave Functions ◽

Localized States ◽

Two Dimensional ◽

Electron Systems ◽

Dimensional Electron ◽

Spin Orbital ◽

Orbital Interactions ◽

Two Dimensional Electron Systems

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Sagnac effect observation in flat and curved spacetime by interference of the opposite topological charge optical vortices

Classical and Quantum Gravity ◽

10.1088/0264-9381/28/15/155011 ◽

2011 ◽

Vol 28 (15) ◽

pp. 155011

Author(s):

I Zeylikovich ◽

J Malinsky

Keyword(s):

Topological Charge ◽

Sagnac Effect ◽

Optical Vortices ◽

Curved Spacetime

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Topological charge and angular momentum of light beams carrying optical vortices

Optical Angular Momentum ◽

10.1887/0750309016/b1142c26 ◽

2004 ◽

Author(s):

M S Soskin ◽

V N Gorshkov ◽

M V Vasnctsov ◽

J T Malos ◽

N R Heckenberg

Keyword(s):

Angular Momentum ◽

Topological Charge ◽

Optical Vortices ◽

Light Beams

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Strongly Focused Circularly Polarized Optical Vortices Regulated by a Fractal Conical Lens

Applied Sciences ◽

10.3390/app10010028 ◽

2019 ◽

Vol 10 (1) ◽

pp. 28

Author(s):

Zhirong Liu ◽

Kelin Huang ◽

Anlian Yang ◽

Xun Wang ◽

Philip H. Jones

Keyword(s):

Angular Momentum ◽

Optical Tweezers ◽

Numerical Aperture ◽

Optical Element ◽

Optical Vortex ◽

Optical Vortices ◽

Circularly Polarized ◽

Strong Focusing ◽

New Type ◽

Vortex Beams

In this paper, a recently-proposed pure-phase optical element, the fractal conical lens (FCL), is introduced for the regulation of strongly-focused circularly-polarized optical vortices in a high numerical aperture (NA) optical system. Strong focusing characteristics of circularly polarized optical vortices through a high NA system in cases with and without a FCL are investigated comparatively. Moreover, the conversion between spin angular momentum (SAM) and orbital angular momentum (OAM) of the focused optical vortex in the focal vicinity is also analyzed. Results revealed that a FCL of different stage S could significantly regulate the distributions of tight focusing intensity and angular momentum of the circularly polarized optical vortex. The interesting results obtained here may be advantageous when using a FCL to shape vortex beams or utilizing circularly polarized vortex beams to exploit new-type optical tweezers.

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The XXL Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730709 ◽

2018 ◽

Vol 620 ◽

pp. A7 ◽

Cited By ~ 9

Author(s):

V. Guglielmo ◽

B. M. Poggianti ◽

B. Vulcani ◽

C. Adami ◽

F. Gastaldello ◽

...

Keyword(s):

Mass Function ◽

Stellar Mass ◽

X Ray ◽

Field Versus ◽

Final Sample ◽

Wide Range ◽

The Galaxy ◽

Halo Masses ◽

Stellar Masses ◽

Physical Phenomena

Context. The fraction of galaxies bound in groups in the nearby Universe is high (50% at z ~ 0). Systematic studies of galaxy properties in groups are important in order to improve our understanding of the evolution of galaxies and of the physical phenomena occurring within this environment. Aims. We have built a complete spectrophotometric sample of galaxies within X-ray detected, optically spectroscopically confirmed groups and clusters (G&C), covering a wide range of halo masses at z ≤ 0.6. Methods. In the context of the XXL survey, we analyse a sample of 164 G&C in the XXL-North region (XXL-N), at z ≤ 0.6, with a wide range of virial masses (1.24 × 1013 ≤ M500,scal(M⊙) ≤ 6.63 × 1014) and X-ray luminosities ((2.27 × 1041 ≤ L500,scalXXL(erg s−1) ≤ 2.15 × 1044)). The G&C are X-ray selected and spectroscopically confirmed. We describe the membership assignment and the spectroscopic completeness analysis, and compute stellar masses. As a first scientific exploitation of the sample, we study the dependence of the galaxy stellar mass function (GSMF) on global environment. Results. We present a spectrophotometric characterisation of the G&C and their galaxies. The final sample contains 132 G&C, 22 111 field galaxies and 2225 G&C galaxies with r-band magnitude <20. Of the G&C, 95% have at least three spectroscopic members, and 70% at least ten. The shape of the GSMF seems not to depend on environment (field versus G&C) or X-ray luminosity (used as a proxy for the virial mass of the system). These results are confirmed by the study of the correlation between mean stellar mass of G&C members and L500,scalXXL. We release the spectrophotometric catalogue of galaxies with all the quantities computed in this work. Conclusions. As a first homogeneous census of galaxies within X-ray spectroscopically confirmed G&C at these redshifts, this sample will allow environmental studies of the evolution of galaxy properties.

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