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Articles 1 - 30 of 78
Full-Text Articles in Physics
Equivalent Dynamical Complexity In A Many-Body Quantum And Collective Human System, Neil F. Johnson, Josef Ashkenazi, Zhenyuan Zhao, Luis Quiroga
Equivalent Dynamical Complexity In A Many-Body Quantum And Collective Human System, Neil F. Johnson, Josef Ashkenazi, Zhenyuan Zhao, Luis Quiroga
Physics Articles and Papers
Proponents of Complexity Science believe that the huge variety of emergent phenomena observed throughout nature, are generated by relatively few microscopic mechanisms. Skeptics however point to the lack of concrete examples in which a single mechanistic model manages to capture relevant macroscopic and microscopic properties for two or more distinct systems operating across radically different length and time scales. Here we show how a single complexity model built around cluster coalescence and fragmentation, can cross the fundamental divide between many-body quantum physics and social science. It simultaneously (i) explains a mysterious recent finding of Fratini et al. concerning quantum many-body …
Color Changes In Stochastic Light Fields Propagating In Non-Kolmogorov Turbulence, Olga Korotkova, Elena Shchepakina
Color Changes In Stochastic Light Fields Propagating In Non-Kolmogorov Turbulence, Olga Korotkova, Elena Shchepakina
Physics Articles and Papers
The dependence of spectral shifts and switches in optical stochastic beams propagating through nonclassic turbulent medium on the slope of the power spectrum of fluctuations in the refractive index is revealed.
Spatio-Temporal Coupling Of Random Electromagnetic Pulses Interacting With Reflecting Gratings, Min Yao, Yangjian Cai, Olga Korotkova, Qiang Lin, Zhaoying Wang
Spatio-Temporal Coupling Of Random Electromagnetic Pulses Interacting With Reflecting Gratings, Min Yao, Yangjian Cai, Olga Korotkova, Qiang Lin, Zhaoying Wang
Physics Articles and Papers
Matrix optics is applied to a class of random, in time and space, electromagnetic pulsed beam-like (REMPB) radiation interacting with linear optical elements. A 66 order matrix describing transformation of a six-dimensional state vector including four spatial and two temporal positions within the field is used to derive conditions for spatio-temporal coupling. An example is included which deals with a spatio-temporal coupling in a typical REMPB on reflection from a reflecting grating. Electromagnetic nature of such interaction is explored via considering dependence of the degree of polarization of the reflected REMPB on its source and on the structure of the …
Propagation Factor Of A Stochastic Electromagnetic Gaussian Schell-Model Beam, Shijun Zhu, Yangjian Cai, Olga Korotkova
Propagation Factor Of A Stochastic Electromagnetic Gaussian Schell-Model Beam, Shijun Zhu, Yangjian Cai, Olga Korotkova
Physics Articles and Papers
Analytical formula is derived for the propagation factor (known asM2-factor) of a stochastic electromagnetic Gaussian Schell-model (EGSM) beam in free space and in turbulent atmosphere. In free space, the M2-factor of an EGSM beam is mainly determined by its initial degree of polarization, r.m.s. widths of the spectral densities and correlation coefficients, and its value remains invariant on propagation. In turbulent atmosphere, the M2-factor of an EGSM beam is also determined by the parameters of the turbulent atmosphere, and its value increases on propagation. The relative M2-factor of an EGSM beam with …
Focusing Of A Femtosecond Vortex Light Pulse Through A High Numerical Aperture Objective, Baosuan Chen, Jixiong Pu, Olga Korotkova
Focusing Of A Femtosecond Vortex Light Pulse Through A High Numerical Aperture Objective, Baosuan Chen, Jixiong Pu, Olga Korotkova
Physics Articles and Papers
We investigate the focusing properties of a femtosecond vortex light pulse focused by a high numerical aperture objective. By using the Richards-Wolf vectorial diffraction method, the intensity distribution, the velocity variation and the orbital angular momentum near the focus are studied in great detail. We have discovered that the femtosecond vortex light pulse can travel at various speeds, that is, slower or faster than light with a tight focusing system. Moreover, we have found that the numerical aperture of the focusing objective and the duration of the vortex light pulse will influence the orbital angular momentum distribution in the focused …
Second-Order Statistics Of Stochastic Electromagnetic Beams Propagating Through Non-Kolmogorov Turbulence, Elena Shchepakina, Olga Korotkova
Second-Order Statistics Of Stochastic Electromagnetic Beams Propagating Through Non-Kolmogorov Turbulence, Elena Shchepakina, Olga Korotkova
Physics Articles and Papers
We present a detailed investigation, qualitative and quantitative, on how the atmospheric turbulence with a non-Kolmogorov power spectrum affects the major statistics of stochastic electromagnetic beams, such as the spectral composition and the states of coherence and polarization. We suggest a detailed survey on how these properties evolve on propagation of beams generated by electromagnetic Gaussian Schell-model sources, depending on the fractal constant α of the atmospheric power spectrum.
Degree Of Paraxiality Of A Partially Coherent Field, Fei Wang, Yangjian Cai, Olga Korotkova
Degree Of Paraxiality Of A Partially Coherent Field, Fei Wang, Yangjian Cai, Olga Korotkova
Physics Articles and Papers
We extend the concept of the degree of paraxiality, introduced recently for monochromatic fields, to the domain of stochastic fields. As an example we analytically evaluate the degree of paraxiality for a broad class of model stochastic fields, the Gaussian Schell-model fields, without and with truncation and twist phase. The dependence of the degree of paraxiality on the size and the state of coherence of the source as well as on the truncation parameter and the magnitude of twist phase is analyzed by a number of numerical examples.
Stochastic Electromagnetic Beams In Positive-And Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Stochastic Electromagnetic Beams In Positive-And Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
Theoretical analysis of interaction of stochastic electromagnetic beamlike fields with positive- and negative-phase materials suggests that suitable combinations of such materials can serve as media where spectral, coherence, and polarization properties of beams can self-reconstruct.
Spectral Shifts And Switches In Random Fields Upon Interaction With Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Spectral Shifts And Switches In Random Fields Upon Interaction With Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
Spectral shifts in stochastic beam-like fields on interaction with layers of positive- and negative-phase materials are examined on the basis of the ABCD-matrix approach and generalized Huygens-Fresnel principle. It is found that boundaries between such materials may cause spectral switches. Effect of absorption of negative-phase materials on the beam spectrum is discussed. Our results may find applications in connection with spectrum-selection optical interconnects, spectrally encoded information transfer, image formation in systems involving negative-phase materials, and geometrically tunable metamaterials.
Theory Of Weak Scattering Of Stochastic Electromagnetic Fields From Deterministic And Random Media, Zhisong Tong, Olga Korotkova
Theory Of Weak Scattering Of Stochastic Electromagnetic Fields From Deterministic And Random Media, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
The theory of scattering of scalar stochastic fields from deterministic and random media is generalized to the electromagnetic domain under the first-order Born approximation. The analysis allows for determining the changes in spectrum, coherence, and polarization of electromagnetic fields produced on their propagation from the source to the scattering volume, interaction with the scatterer, and propagation from the scatterer to the far field. An example of scattering of a field produced by a δ-correlated partially polarized source and scattered from a δ-correlated medium is provided.
Partially Coherent Standard And Elegant Laguerre-Gaussian Beams Of All Orders, Fei Wang, Yangjian Cai, Olga Korotkova
Partially Coherent Standard And Elegant Laguerre-Gaussian Beams Of All Orders, Fei Wang, Yangjian Cai, Olga Korotkova
Physics Articles and Papers
Partially coherent standard and elegant Laguerre-Gaussian (LG) beams of all orders are introduced as a natural extension of coherent standard and elegant LG beams to the stochastic domain. By expanding the LG modes into a finite sum of Hermite-Gaussian modes, the analytical formulae are obtained for the cross-spectral densities of partially coherent standard and elegant LG beams in the source plane and after passing through paraxial ABCD optical system, based on the generalized Collins integral formula. A comparative study of the propagation properties of the partially coherent standard and elegant LG beams in free space is carried out via a …
Radiation Force Of Scalar And Electromagnetic Twisted Gaussian Schell-Model Beams, Chengliang Zhao, Yangjian Cai, Olga Korotkova
Radiation Force Of Scalar And Electromagnetic Twisted Gaussian Schell-Model Beams, Chengliang Zhao, Yangjian Cai, Olga Korotkova
Physics Articles and Papers
Radiation force of a focused scalar twisted Gaussian Schell-model (TGSM) beam on a Rayleigh dielectric sphere is investigated. It is found that the twist phase affects the radiation force and by raising the absolute value of the twist factor it is possible to increase both transverse and longitudinal trapping ranges at the real focus where the maximum on-axis intensity is located. Numerical calculations of radiation forces induced by a focused electromagnetic TGSM beam on a Rayleigh dielectric sphere are carried out. It is found that radiation force is closely related to the twist phase, degree of polarization and correlation factors …
M2-Factor Of Coherent And Partially Coherent Dark Hollow Beams Propagating In Turbulent Atmosphere, Yangsheng Yuan, Yangjian Cai, Jun Qu, Halil T. Eyyuboglu, Yahya Baykal, Olga Korotkova
M2-Factor Of Coherent And Partially Coherent Dark Hollow Beams Propagating In Turbulent Atmosphere, Yangsheng Yuan, Yangjian Cai, Jun Qu, Halil T. Eyyuboglu, Yahya Baykal, Olga Korotkova
Physics Articles and Papers
Analytical formula is derived for the M2-factor of coherent and partially coherent dark hollow beams (DHB) in turbulent atmosphere based on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function. Our numerical results show that the M2- factor of a DHB in turbulent atmosphere increases on propagation, which is much different from its invariant properties in free-space, and is mainly determined by the parameters of the beam and the atmosphere. The relative M2-factor of a DHB increases slower than that of Gaussian and flat-topped beams on propagation, which means a …
Scintillation Of Nonuniformly Polarized Beams In Atmospheric Turbulence, Yalong Gu, Olga Korotkova, Greg Gbur
Scintillation Of Nonuniformly Polarized Beams In Atmospheric Turbulence, Yalong Gu, Olga Korotkova, Greg Gbur
Physics Articles and Papers
We demonstrate, through numerical simulations, that an appropriately chosen nonuniformly polarized coherent optical field can have appreciably smaller scintillation than comparable beams of uniform polarization. This results from the fact that a nonuniformly polarized field acts as an effective two-mode partially coherent field. The results described here are of direct relevance to the development of free-space optical communication systems.
Effect Of The Pair-Structure Factor Of A Particulate Medium On Scalar Wave Scattering In The First Born Approximation, Serkan Sahin, Olga Korotkova
Effect Of The Pair-Structure Factor Of A Particulate Medium On Scalar Wave Scattering In The First Born Approximation, Serkan Sahin, Olga Korotkova
Physics Articles and Papers
Using scattering matrices and the angular spectrum representation of waves, we develop the analytical theory of scattering of random scalar waves from random collections of particles, valid under the first Born approximation. We demonstrate that in the calculation of far-field statistics, such as the spectral density and the spectral degree of coherence, the knowledge of the pair-structure factor of the collection is crucial. We illustrate our analytical approach by considering a numerical example involving scattering of two partially correlated plane waves from a random distribution of spheres.
Scintillation Index Of Modified Bessel–Gaussian Beams Propagating In Turbulent Media, Halil T. Eyyuboglu, Yahya Baykal, Emre Sermutlu, Olga Korotkova, Yangjian Cai
Scintillation Index Of Modified Bessel–Gaussian Beams Propagating In Turbulent Media, Halil T. Eyyuboglu, Yahya Baykal, Emre Sermutlu, Olga Korotkova, Yangjian Cai
Physics Articles and Papers
The scintillation index is formulated for modified Bessel-Gaussian beams propagating in weakly turbulent media. Numerical calculations applied directly to the derived triple integral show that, for off-axis positions, the modified Bessel-Gaussian beams of higher than zero order scintillate less than Gaussian beams at large input beam sizes and low beam orders with the increasing width parameter initially contributing positively to this phenomenon of less scintillation. As the beam order exceeds two, this advantage is diminished. The modified Bessel-Gaussian beam of order zero is a special case, however, exhibiting lowest scintillation at small input beam sizes. When considered against the propagation …
Ghost Imaging With Twisted Gaussian Schell-Model Beam, Yangjian Cai, Qiang Lin, Olga Korotkova
Ghost Imaging With Twisted Gaussian Schell-Model Beam, Yangjian Cai, Qiang Lin, Olga Korotkova
Physics Articles and Papers
Based on the classical optical coherence theory, ghost imaging with twisted Gaussian Schell-model (GSM) beams is analyzed. It is found that the twist phase of the GSM beam has strong influence on ghost imaging. As the absolute value of the twist factor increases, the ghost image disappears gradually, but its visibility increases. This phenomenon is caused by the fact that the twist phase enhances the transverse spatial coherence of the twisted GSM beam on propagation.
Electrical Measurements Of The Polarization In A Moving Magnetic Vortex, Jun-Ichiro Ohe, Stewart E. Barnes, Hyun-Woo Lee, Sadamichi Maekawa
Electrical Measurements Of The Polarization In A Moving Magnetic Vortex, Jun-Ichiro Ohe, Stewart E. Barnes, Hyun-Woo Lee, Sadamichi Maekawa
Physics Articles and Papers
We propose that the polarization of the moving magnetic vortex core can be detected by the electro- and spin-motive forces acting on the spin-polarized conduction electrons. With parameters appropriate to Permalloy, we have simulated the dynamics of a magnetic vortex core resulting from an applied oscillating magnetic field. We show that the polarization of the moving core can be detected by a simple electrical measurement.
State Of Polarization Of A Stochastic Electromagnetic Beam In An Optical Resonator, Olga Korotkova, Min Yao, Yangjian Cai, Halil T. Eyyuboglu, Yahya Baykal
State Of Polarization Of A Stochastic Electromagnetic Beam In An Optical Resonator, Olga Korotkova, Min Yao, Yangjian Cai, Halil T. Eyyuboglu, Yahya Baykal
Physics Articles and Papers
On the basis of the unified theory of coherence and polarization, we investigate the behavior of the state of polarization of a stochastic electromagnetic beam in a Gaussian cavity. Formulations both in terms of Stokes parameters and in terms of polarization ellipse are given. We show that the state of polarization stabilizes, except in the case of a lossless cavity, after several passages between the mirrors, exhibiting monotonic or oscillatory behavior depending on the parameters of the resonator. We also find that an initially (spatially) uniformly polarized beam remains nonuniformly polarized even for a large number of passages between the …
Evolution Of The Degree Of Polarization Of An Electromagnetic Gaussian Schell-Model Beam In A Gaussian Cavity, Min Yao, Yangjian Cai, Halil T. Eyyuboglu, Yahya Baykal, Olga Korotkova
Evolution Of The Degree Of Polarization Of An Electromagnetic Gaussian Schell-Model Beam In A Gaussian Cavity, Min Yao, Yangjian Cai, Halil T. Eyyuboglu, Yahya Baykal, Olga Korotkova
Physics Articles and Papers
The interaction of an electromagnetic Gaussian Schell-model (EGSM) beam with a Gaussian cavity is analyzed. In particular, the evolution of the degree of polarization of the EGSM beam is investigated. The results show that the behavior of the degree of polarization depends on both the statistical properties of the source that generates the EGSM beam and the parameters of the cavity.
Active Laser Radar Systems With Stochastic Electromagnetic Beams In Turbulent Atmosphere, Yangjian Cai, Olga Korotkova, Halil T. Eyyuboğlu, Yahya Baykal
Active Laser Radar Systems With Stochastic Electromagnetic Beams In Turbulent Atmosphere, Yangjian Cai, Olga Korotkova, Halil T. Eyyuboğlu, Yahya Baykal
Physics Articles and Papers
Propagation of stochastic electromagnetic beams through paraxial ABCD optical systems operating through turbulent atmosphere is investigated with the help of the ABCD matrices and the generalized Huygens-Fresnel integral. In particular, the analytic formula is derived for the cross-spectral density matrix of an electromagnetic Gaussian Schell-model (EGSM) beam. We applied our analysis for the ABCD system with a single lens located on the propagation path, representing, in a particular case, the unfolded double-pass propagation scenario of active laser radar. Through a number of numerical examples we investigated the effect of local turbulence strength and lens' parameters on spectral, coherence and polarization …
Scattering Of Scalar Light Fields From Collections Of Particles, Serkan Sahin, Olga Korotkova
Scattering Of Scalar Light Fields From Collections Of Particles, Serkan Sahin, Olga Korotkova
Physics Articles and Papers
Using the angular spectrum representation of fields and the first Born approximation we develop a theory of scattering of scalar waves with any spectral composition and any correlation properties from collections of particles which have either deterministic or random distributions of the index of refraction and locations. An example illustrating the far-field intensity and the far-field spectral degree of coherence produced on scattering of a model field from collections of several particles with Gaussian potentials is considered.
Changes In The Statistical Properties Of Stochastic Anisotropic Electromagnetic Beams On Propagation In The Turbulent Atmosphere, Xinyue Du, Daomu Zhao, Olga Korotkova
Changes In The Statistical Properties Of Stochastic Anisotropic Electromagnetic Beams On Propagation In The Turbulent Atmosphere, Xinyue Du, Daomu Zhao, Olga Korotkova
Physics Articles and Papers
We report analytic formulas for the elements of the e 2 X 2 cross-spectral density matrix of a stochastic electromagnetic anisotropic beam propagating through the turbulent atmosphere with the help of vector integration. From these formulas the changes in the spectral density (spectrum), in the spectral degree of polarization, and in the spectral degree of coherence of such a beam on propagation are determined. As an example, these quantities are calculated for a so-called anisotropic electromagnetic Gaussian Schell-model beam propagating in the isotropic and homogeneous atmosphere. In particular, it is shown numerically that for a beam of this class, unlike …
Application Of Correlation-Induced Spectral Changes To Inverse Scattering, Daomu Zhao, Olga Korotkova, Emil Wolf
Application Of Correlation-Induced Spectral Changes To Inverse Scattering, Daomu Zhao, Olga Korotkova, Emil Wolf
Physics Articles and Papers
It is shown how the phenomenon of correlation-induced spectral changes generated on scattering of a polychromatic plane wave on a spatially homogeneous random medium may be used to determine the correlation function of the scattering potential of the medium.
Angular Spectrum Representation For Propagation Of Random Electromagnetic Beams In A Turbulent Atmosphere, Olga Korotkova, Greg Gbur
Angular Spectrum Representation For Propagation Of Random Electromagnetic Beams In A Turbulent Atmosphere, Olga Korotkova, Greg Gbur
Physics Articles and Papers
The combination of an angular spectrum representation (in the space-frequency domain) and the second-order Rytov perturbation theory is applied for description of the second-order statistical properties of arbitrary (coherent and partially coherent) stochastic electromagnetic beamlike fields that propagate in a turbulent atmosphere. In particular, we derive the expressions for the elements of the cross-spectral density matrix of the beam, from which its spectral, coherence, and polarization properties can be found. We illustrate the method by applying it to the propagation of several electromagnetic model beams through the atmosphere.
Beam Criterion For Atmospheric Propagation, Olga Korotkova, Emil Wolf
Beam Criterion For Atmospheric Propagation, Olga Korotkova, Emil Wolf
Physics Articles and Papers
A criterion is introduced for testing whether a beam retains its beam-like form after it propagates any particular distance through the turbulent atmosphere. The criterion applies to monochromatic as well as to partially coherent beams and is illustrated by examples.
Definitions Of The Degree Of Polarization Of A Light Beam, Asma Al-Qasimi, Olga Korotkova, Daniel James, Emil Wolf
Definitions Of The Degree Of Polarization Of A Light Beam, Asma Al-Qasimi, Olga Korotkova, Daniel James, Emil Wolf
Physics Articles and Papers
A necessary and sufficient condition is derived for certain ad hoc expressions that are frequently used in the literature to represent correctly the degree of polarization of a light beam.
Angular Spectrum Representation For The Propagation Of Arbitrary Coherent And Partially Coherent Beams Through Atmospheric Turbulence, Greg Gbur, Olga Korotkova
Angular Spectrum Representation For The Propagation Of Arbitrary Coherent And Partially Coherent Beams Through Atmospheric Turbulence, Greg Gbur, Olga Korotkova
Physics Articles and Papers
An angular spectrum representation is applied for a description of statistical properties of arbitrary beamlike fields propagating through atmospheric turbulence. The Rytov theory is used for the characterization of the perturbation of the field by the atmosphere. In particular, we derive expressions for the cross-spectral density of a coherent and a partially coherent beam of arbitrary type in the case when the power spectrum of atmospheric fluctuations is described by the von Karman model. We illustrate the method by applying it to the propagation of several model beams through the atmosphere.
Can Two Planar Sources With The Same Sets Of Stokes Parameters Generate Beams With Different Degrees Of Polarization?, Mohamed Salem, Olga Korotkova, Emil Wolf
Can Two Planar Sources With The Same Sets Of Stokes Parameters Generate Beams With Different Degrees Of Polarization?, Mohamed Salem, Olga Korotkova, Emil Wolf
Physics Articles and Papers
It is shown that two stochastic electromagnetic beams that propagate from the source plane z=0 into the half-space z>0 may have different degrees of polarization throughout the half-space, even though they have the same sets of Stokes parameters in the source plane. This fact is due to a possible difference in the coherence properties of the field in that plane, but other reasons are also possible. The result is illustrated by an example.
Invariance And Noninvariance Of The Spectra Of Stochastic Electromagnetic Beams On Propogation, Jixiong Pu, Olga Korotkova, Emil Wolf
Invariance And Noninvariance Of The Spectra Of Stochastic Electromagnetic Beams On Propogation, Jixiong Pu, Olga Korotkova, Emil Wolf
Physics Articles and Papers
It has been known for some time that the spectrum of light may change on propagation, even in free space. The theory of this phenomenon was developed within the framework of scalar theory. We generalize it to electromagnetic beams, generated by planar, secondary, stochastic sources. We also derive an electromagnetic analog of the so-called scaling law. When this law is satisfied the normalized spectrum of the beam is the same throughout the far zone and across the source.