196 research outputs found
Modern technologies as a threat to the national mentality
Relevance. The national mentality is the fundamental basis of a nation existence. It increases the adaptive potential of its native speakers, allows them to preserve their identity and exist as a single group united by nationality. Modern technologies as an integral attribute of the present inevitably interact with the national mentality, which is an important component of the life of society. Subject. Destructive potential of modern technologies in relation to the national mentality. Therefore, the author considered informational, cognitive and psychological technologies among the many varieties of modern ones. Since they act as channels for transmitting destructive information that threatens the national mentality, which is a source of information for the nation in all significant spheres of life. Aim. To consider the declared modern technologies as threats to the national mentality as the basis of society vital activity. Methods. A philosophical and cultural approach, as well as psychological and anthropological analysis, through which the foundations of a modern society existence were discovered. The society despite its focus on technological progress and the possibilities of modern technologies, does not completely deviate from the values of the national mentality. Results. The author determined the influence of modern technologies on the national mentality, which is of a negative nature. This allows us to summarize that new technologies not only simplify life and bring it to a higher level of development, but also undermine its foundations, becoming a threat. Conclusions. Modern technologies can pose a threat to the national mentality if they are used in information, cognitive and psychological wars, as well as in the case of ill-conceived actions aimed at positively influencing it. Often, the war of meanings (the war of the new generation) is referred to as an information and psychological war using the latest achievements of science and technology, including information, cognitive and psychological tools. Further research in this area is very promising, since at present the confrontation between two opposite processes β globalization and regionalization β is growing, intercivilizational contradictions are increasing, and developments in the field of improving methods of non-kinetic warfare, which often appears as an image of the Third World war, are continuing
Vortex-free laser beam with an orbital angular momentum
We show that if one cylindrical lens is placed in the Gaussian beam waist and another cylindrical lens is placed at some distance from the first one and rotated by some angle, then the laser beam after the second lens has an orbital angular momentum (OAM). An explicit analytical expression for the OAM of such a beam is obtained. Depending on the inter-lens distance, the OAM can be positive, negative, or zero. Such a laser beam has no isolated intensity nulls with a singular phase and it is not an optical vortex, but has an OAM. By choosing the radius of the beam waist of the source Gaussian beam, the focal lengths of the lenses and the distance between them, it is possible to generate a vortex-free laser beam equivalent to an optical vortex with a topological charge of several hundreds.This work was funded by the Russian Science Foundation grant # 17-19-0118
Controlling the orbital angular momentum of Gaussian vortices by shifting the point of phase singularity
A simple formula is obtained to describe the normalized orbital angular momentum (OAM) of a Gaussian beam after passing through a shifter spiral phase plate (SPP). The formula shows that while being equal to the topological charge at the zero off-axis shift, the OAM becomes fractional with increasing shift and it is tending to zero exponentially. Analytic expressions of the complex amplitude of the Gaussian beam having passed through the off-axis SPP show that as the beam propagates, the isolated intensity null moves from the initial point defined by the vector of the SPP's center shift along a straight line perpendicular to the said vector. Using a liquid crystal light modulator, crescent-shaped beams are experimentally generated.This work was supported by the Federal Agency of Scientific Organizations (agreement No 007-ΠΠ/Π§3363/26) and funded by the Russian Science Foundation (RSF), grant No. 17-19-01186
Topological charge of a superposition of two Bessel-Gaussian beams
Π ΡΠ°Π±ΠΎΡΠ΅ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Ρ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ Π΄Π²ΡΡ
ΠΏΡΡΠΊΠΎΠ² ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ° Ρ ΡΠ°Π·Π½ΡΠΌΠΈ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ Π·Π°ΡΡΠ΄Π°ΠΌΠΈ ΠΈ ΡΠ°Π·Π½ΡΠΌΠΈ ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΠΌΠΈ ΠΌΠ½ΠΎΠΆΠΈΡΠ΅Π»ΡΠΌΠΈ (ΡΠ°Π΄ΠΈΠ°Π»ΡΠ½ΡΠΌΠΈ ΠΏΡΠΎΠ΅ΠΊΡΠΈΡΠΌΠΈ Π²ΠΎΠ»Π½ΠΎΠ²ΡΡ
Π²Π΅ΠΊΡΠΎΡΠΎΠ²) ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΠ°Π²Π΅Π½ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌΡ Π·Π°ΡΡΠ΄Ρ ΡΠΎΠ³ΠΎ ΠΏΡΡΠΊΠ° ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ°, Ρ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ Π±ΠΎΠ»ΡΡΠ΅ ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΠΉ ΠΌΠ½ΠΎΠΆΠΈΡΠ΅Π»Ρ. ΠΡΠ»ΠΈ Ρ ΠΏΡΡΠΊΠΎΠ² ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ° ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΠ΅ ΠΌΠ½ΠΎΠΆΠΈΡΠ΅Π»ΠΈ ΡΠ°Π²Π½Ρ, ΡΠΎ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ ΡΠ°Π²Π΅Π½ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌΡ Π·Π°ΡΡΠ΄Ρ ΡΠΎΠ³ΠΎ ΠΏΡΡΠΊΠ° ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ°, Ρ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ Π±ΠΎΠ»ΡΡΠ΅ ΠΌΠΎΠ΄ΡΠ»Ρ Π²Π΅ΡΠΎΠ²ΠΎΠ³ΠΎ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° (Π±ΠΎΠ»ΡΡΠ΅ ΠΌΠΎΡΠ½ΠΎΡΡΡ). ΠΡΠ»ΠΈ ΠΈ ΠΌΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΡΡΠΊΠΎΠ² ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²Ρ, ΡΠΎ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ ΡΠ°Π²Π΅Π½ ΡΡΠ΅Π΄Π½Π΅ΠΌΡ Π°ΡΠΈΡΠΌΠ΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΌΡ ΠΎΡ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
Π·Π°ΡΡΠ΄ΠΎΠ² ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΏΡΡΠΊΠ° ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ° Π² ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ. ΠΡΠΈ ΡΡΠ»ΠΎΠ²ΠΈΠΈ, ΡΡΠΎ ΡΡΠΌΠΌΠ° ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
Π·Π°ΡΡΠ΄ΠΎΠ² ΠΎΠ±ΠΎΠΈΡ
ΠΏΡΡΠΊΠΎΠ² Π½Π΅ΡΡΡΠ½Π°Ρ, ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ Π±ΡΠ΄Π΅Ρ ΠΏΠΎΠ»ΡΡΠ΅Π»ΡΠΌ ΡΠΈΡΠ»ΠΎΠΌ. ΠΠΎ Π½Π° ΠΏΡΠ°ΠΊΡΠΈΠΊΠ΅ ΠΈΠ·-Π·Π° ΠΊΠΎΠ½Π΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π΄ΠΈΡΡΠ° ΠΎΠΊΡΡΠΆΠ½ΠΎΡΡΠΈ, Π½Π° ΠΊΠΎΡΠΎΡΠΎΠΌ ΡΠ°ΡΡΡΠΈΡΡΠ²Π°Π΅ΡΡΡ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄, ΠΏΠΎΠ»ΡΡΠ΅Π»ΠΎΠ³ΠΎ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π° Π΄Π»Ρ Π²ΡΡΠΎΠΆΠ΄Π΅Π½Π½ΠΎΠ³ΠΎ ΡΠ»ΡΡΠ°Ρ Π½Π΅ ΠΏΠΎΠ»ΡΡΠ°Π΅ΡΡΡ. ΠΠΌΠ΅ΡΡΠΎ ΠΏΠΎΠ»ΡΡΠ΅Π»ΠΎΠ³ΠΎ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π°, ΠΏΠΎΠ»ΡΡΠ°Π΅ΡΡΡ ΡΠ΅Π»ΡΠΉ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄, ΠΌΠ΅Π½ΡΡΠΈΠΉ ΠΈΠ· Π΄Π²ΡΡ
. ΠΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ, ΡΡΠΎ ΠΏΡΠΈ Π½Π΅Π±ΠΎΠ»ΡΡΠΎΠΉ ΡΠ°Π·Π½ΠΈΡΠ΅ Π² Π²Π΅ΡΠΎΠ²ΡΡ
ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ°Ρ
ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ Π½Π΅ ΡΠΎΡ
ΡΠ°Π½ΡΠ΅ΡΡΡ: Π² Π±Π»ΠΈΠΆΠ½Π΅ΠΉ Π·ΠΎΠ½Π΅ ΠΈ Π·ΠΎΠ½Π΅ Π€ΡΠ΅Π½Π΅Π»Ρ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΠ°Π²Π΅Π½ Π±ΠΎΠ»ΡΡΠ΅ΠΌΡ ΠΈΠ· Π΄Π²ΡΡ
, Π° Π² Π΄Π°Π»ΡΠ½Π΅ΠΉ Π·ΠΎΠ½Π΅ β ΠΌΠ΅Π½ΡΡΠ΅ΠΌΡ. ΠΡΠΈΡΠ΅ΠΌ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π° ΠΎΡ Π±ΠΎΠ»ΡΡΠ΅Π³ΠΎ ΠΊ ΠΌΠ΅Π½ΡΡΠ΅ΠΌΡ ΠΏΡΠΎΠΈΡΡ
ΠΎΠ΄ΠΈΡ Π½Π΅ ΡΠΊΠ°ΡΠΊΠΎΠΌ, Π° Π½Π΅ΠΏΡΠ΅ΡΡΠ²Π½ΠΎ Π½Π° Π½Π΅ΠΊΠΎΡΠΎΡΠΎΠΌ ΡΠ°ΡΡΡΠΎΡΠ½ΠΈΠΈ. Π ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄Π½ΠΎΠΉ Π·ΠΎΠ½Π΅ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ Π΄ΡΠΎΠ±Π½ΡΠΉ.
Here we show theoretically that a superposition of two Bessel-Gaussian (BG) beams with different topological charges (TC) and different scaling factors (radial components of the wave vectors) has the TC equal to that of the BG beam with the larger scaling factor. If the scaling factors of the BG beams are equal, then TC of the whole superposition equals TC of the BG beam with the larger (in absolute value) weight coefficient in the superposition (i.e. with larger power). If the constituent BG beams are also same-power, TC of the superposition equals the average TC of the two BG beams. Therefore, if the sum of TCs of both beams is odd, TC of the superposition is a half-integer number. In practice, however, TC is calculated over a finite radius circle and, hence, the half-integer TC for the degenerated case cannot be obtained. Instead of the half-integer TC, the lower of the two integer TCs is obtained. Numerical simulation reveals that if the weight coefficients in the superposition are slightly different, TC of the superposition is not conserved on propagation. In the near field and in the Fresnel diffraction zone, TC is equal to the highest TC of the two BG beams, while in the far field it is equal to the lower TC. What is more, TC changes its value from high to low not instantly, but continuously at some propagation distance. In the intermediate zone TC is fractional.Π Π°Π±ΠΎΡΠ° Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΏΡΠΈ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠ΅ Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° ΡΡΠ½Π΄Π°ΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ (Π³ΡΠ°Π½Ρ 18-29-20003 Π² ΡΠ°ΡΡΡΡ
Β«Π Π°ΡΡΠ΅Ρ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π° ΡΡΠΌΠΌΡ Π΄Π²ΡΡ
ΠΏΡΡΠΊΠΎΠ² ΠΠΒ» ΠΈ Β«Π’ΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π·Π°ΡΡΠ΄ ΡΡΠΏΠ΅ΡΠΏΠΎΠ·ΠΈΡΠΈΠΈ Π΄Π²ΡΡ
ΠΏΡΡΠΊΠΎΠ² ΠΠ΅ΡΡΠ΅Π»ΡβΠΠ°ΡΡΡΠ° Ρ ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²ΡΠΌΠΈ Π²Π΅ΡΠΎΠ²ΡΠΌΠΈ ΠΈ ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΠΌΠΈ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ°ΠΌΠΈΒ»), Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ Π½Π°ΡΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° (Π³ΡΠ°Π½Ρ 18-19-00595 Π² ΡΠ°ΡΡΡΡ
Β«ΠΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅Β» ΠΈ Β«ΠΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ Π² ΡΠ»ΡΡΠ°Π΅ ΠΏΡΠΈΠΌΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π²Π΅Π½ΡΡΠ²Π° Π²Π΅ΡΠΎΠ²ΡΡ
ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠΎΠ²Β»), Π° ΡΠ°ΠΊΠΆΠ΅ ΠΠΈΠ½ΠΈΡΡΠ΅ΡΡΡΠ²Π° Π½Π°ΡΠΊΠΈ ΠΈ Π²ΡΡΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π Π€ Π² ΡΠ°ΠΌΠΊΠ°Ρ
Π²ΡΠΏΠΎΠ»Π½Π΅Π½ΠΈΡ ΡΠ°Π±ΠΎΡ ΠΏΠΎ ΠΠΎΡΡΠ΄Π°ΡΡΡΠ²Π΅Π½Π½ΠΎΠΌΡ Π·Π°Π΄Π°Π½ΠΈΡ Π€ΠΠΠ¦ Β«ΠΡΠΈΡΡΠ°Π»Π»ΠΎΠ³ΡΠ°ΡΠΈΡ ΠΈ ΡΠΎΡΠΎΠ½ΠΈΠΊΠ°Β» Π ΠΠ Π² ΡΠ°ΡΡΠΈ Β«ΠΠ²Π΅Π΄Π΅Π½ΠΈΠ΅Β» ΠΈ Β«ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅Β»
Instabilities and Bifurcations of Nonlinear Impurity Modes
We study the structure and stability of nonlinear impurity modes in the
discrete nonlinear Schr{\"o}dinger equation with a single on-site nonlinear
impurity emphasizing the effects of interplay between discreteness,
nonlinearity and disorder. We show how the interaction of a nonlinear localized
mode (a discrete soliton or discrete breather) with a repulsive impurity
generates a family of stationary states near the impurity site, as well as
examine both theoretical and numerical criteria for the transition between
different localized states via a cascade of bifurcations.Comment: 8 pages, 8 figures, Phys. Rev. E in pres
Time-optimal algorithms focused on the search for random pulsed-point sources
The article describes methods and algorithms related to the analysis of dynamically changing discrete random fields. Time-optimal strategies for the localization of pulsed-point sources having a random spatial distribution and indicating themselves by generating instant delta pulses at random times are proposed. An optimal strategy is a procedure that has a minimum (statistically) average localization time. The search is performed in accordance with the requirements for localization accuracy and is carried out by a system with one or several receiving devices. Along with the predetermined accuracy of localization of a random pulsed-point source, a significant complicating factor of the formulated problem is that the choice of the optimal search procedure is not limited to one-step algorithms that end at the moment of first pulse generation. Moreover, the article shows that even with relatively low requirements for localization accuracy, the time-optimal procedure consists of several steps, and the transition from one step to another occurs at the time of registration of the next pulse by the receiving system. In this case, the situation is acceptable when during the process of optimal search some of the generated pulses are not fixed by the receiving system. The parameters of the optimal search depending on the number of receiving devices and the required accuracy of localization are calculated and described in the paper.This work was supported in part by the Russian Foundation for Basic Research (projects no 18-51-00001 and 19-01-00128), and Ministry of Science and Higher Education of the Russian Federation (project no. β AAA-A17-117052410034-6)
Transformation of a high-order edge dislocation to optical vortices (spiral dislocations)
Π’Π΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π°ΡΡΠΈΠ³ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΏΡΠ΅ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΊΡΠ°Π΅Π²ΠΎΠΉ Π΄ΠΈΡΠ»ΠΎΠΊΠ°ΡΠΈΠΈ (ΠΏΡΡΠΌΠΎΠΉ Π»ΠΈΠ½ΠΈΠΈ Π½ΡΠ»Π΅Π²ΠΎΠΉ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ) n-Π³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ° ΡΠΎΡΠΌΠΈΡΡΠ΅Ρ Π½Π° Π΄Π²ΠΎΠΉΠ½ΠΎΠΌ ΡΠΎΠΊΡΡΠ½ΠΎΠΌ ΡΠ°ΡΡΡΠΎΡΠ½ΠΈΠΈ ΠΎΡ ΡΠΈΠ»ΠΈΠ½Π΄ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π»ΠΈΠ½Π·Ρ n ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π²ΠΈΡ
ΡΠ΅ΠΉ (Π²ΠΈΠ½ΡΠΎΠ²ΡΡ
Π΄ΠΈΡΠ»ΠΎΠΊΠ°ΡΠΈΠΉ) Ρ Π΅Π΄ΠΈΠ½ΠΈΡΠ½ΡΠΌ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ Π·Π°ΡΡΠ΄ΠΎΠΌ, ΡΠ°ΡΠΏΠΎΠ»ΠΎΠΆΠ΅Π½Π½ΡΡ
Π½Π° ΠΏΡΡΠΌΠΎΠΉ Π»ΠΈΠ½ΠΈΠΈ, ΠΏΠ΅ΡΠΏΠ΅Π½Π΄ΠΈΠΊΡΠ»ΡΡΠ½ΠΎΠΉ ΠΊΡΠ°Π΅Π²ΠΎΠΉ Π΄ΠΈΡΠ»ΠΎΠΊΠ°ΡΠΈΠΈ, Π² ΡΠΎΡΠΊΠ°Ρ
, ΠΊΠΎΠΎΡΠ΄ΠΈΠ½Π°ΡΡ ΠΊΠΎΡΠΎΡΡΡ
ΡΠ²Π»ΡΡΡΡΡ ΠΊΠΎΡΠ½ΡΠΌΠΈ ΠΌΠ½ΠΎΠ³ΠΎΡΠ»Π΅Π½Π° ΠΡΠΌΠΈΡΠ° n-Π³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ°. ΠΡΠ±ΠΈΡΠ°Π»ΡΠ½ΡΠΉ ΡΠ³Π»ΠΎΠ²ΠΎΠΉ ΠΌΠΎΠΌΠ΅Π½Ρ ΠΊΡΠ°Π΅Π²ΠΎΠΉ Π΄ΠΈΡΠ»ΠΎΠΊΠ°ΡΠΈΠΈ Ρ Π°ΡΡΠΈΠ³ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ°Π·ΠΎΠΉ ΠΏΡΠΎΠΏΠΎΡΡΠΈΠΎΠ½Π°Π»Π΅Π½ n.
We theoretically show that an astigmatic transformation of an nth-order edge dislocation (a zero-intensity straight line) produces n optical elliptical vortices (spiral dislocations) with unit topological charge at the double focal distance from the cylindrical lens, located on a straight line perpendicular to the edge dislocation, at points whose coordinates are the roots of an nth-order Hermite polynomial. The orbital angular momentum of the edge dislocation is proportional to the order n.Π Π°Π±ΠΎΡΠ° Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΏΡΠΈ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠ΅ Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° ΡΡΠ½Π΄Π°ΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ (Π³ΡΠ°Π½Ρ 18-29-20003, ΠΏΠ°ΡΠ°Π³ΡΠ°Ρ Β«ΠΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½Π°Ρ Π°ΠΌΠΏΠ»ΠΈΡΡΠ΄Π° ΠΏΠΎΠ»Ρ Ρ ΠΊΡΠ°Π΅Π²ΠΎΠΉ Π΄ΠΈΡΠ»ΠΎΠΊΠ°ΡΠΈΠ΅ΠΉ Π½Π° Π΄Π²ΠΎΠΉΠ½ΠΎΠΌ ΡΠΎΠΊΡΡΠ½ΠΎΠΌ ΡΠ°ΡΡΡΠΎΡΠ½ΠΈΠΈΒ»), Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ Π½Π°ΡΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° (Π³ΡΠ°Π½Ρ 18-19-00595, ΠΏΠ°ΡΠ°Π³ΡΠ°Ρ Β«ΠΡΠ±ΠΈΡΠ°Π»ΡΠ½ΡΠΉ ΡΠ³Π»ΠΎΠ²ΠΎΠΉ ΠΌΠΎΠΌΠ΅Π½ΡΒ»), Π° ΡΠ°ΠΊΠΆΠ΅ ΠΠΈΠ½ΠΈΡΡΠ΅ΡΡΡΠ²Π° Π½Π°ΡΠΊΠΈ ΠΈ Π²ΡΡΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π Π€ Π² ΡΠ°ΠΌΠΊΠ°Ρ
Π²ΡΠΏΠΎΠ»Π½Π΅Π½ΠΈΡ ΡΠ°Π±ΠΎΡ ΠΏΠΎ ΠΠΎΡΡΠ΄Π°ΡΡΡΠ²Π΅Π½Π½ΠΎΠΌΡ Π·Π°Π΄Π°Π½ΠΈΡ Π€ΠΠΠ¦ Β«ΠΡΠΈΡΡΠ°Π»Π»ΠΎΠ³ΡΠ°ΡΠΈΡ ΠΈ ΡΠΎΡΠΎΠ½ΠΈΠΊΠ°Β» Π ΠΠ (ΠΏΠ°ΡΠ°Π³ΡΠ°Ρ Β«ΠΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅Β»)
Magnetothermopower and Nernst effect in unconventional charge density waves
Recently we have shown that the striking angular dependent magnetoresistance
in the low temperature phase (LTP) of alpha-(BEDT-TTF)_2KHg(SCN)_4 is
consistently described in terms of unconventional charge density wave (UCDW).
Here we investigate theoretically the thermoelectric power and the Nernst
effect in UDW. The present results account consistently for the recent data of
magnetothermopower in alpha-(BEDT-TTF)_2KHg(SCN)_4 obtained by Choi et al.
(Phys. Rev. B, 65, 205119 (2002)). This confirms further our identification of
LTP in this salt as UCDW. We propose also that the Nernst effect provides a
clear signature of UDW.Comment: 4 pages, 4 figure
Experimental investigation of the energy backflow in the tight focal spot
Π‘ ΠΏΠΎΠΌΠΎΡΡΡ Π΄Π²ΡΡ
ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²ΡΡ
ΠΌΠΈΠΊΡΠΎΠΎΠ±ΡΠ΅ΠΊΡΠΈΠ²ΠΎΠ² Ρ ΡΠΈΡΠ»ΠΎΠ²ΠΎΠΉ Π°ΠΏΠ΅ΡΡΡΡΠΎΠΉ 0,95 Π±ΡΠ»ΠΎ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΡ Π½Π° ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΡΠΈ Π² ΠΏΠ»ΠΎΡΠΊΠΎΡΡΠΈ ΡΠΎΠΊΡΡΠ° ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²ΠΈΡ
ΡΡ Ρ ΡΠΎΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ Π·Π°ΡΡΠ΄ΠΎΠΌ 2 ΡΠ°Π²Π½Π° Π½ΡΠ»Ρ Π΄Π»Ρ ΡΠ²Π΅ΡΠ° Ρ ΠΏΡΠ°Π²ΠΎΠΉ ΠΊΡΡΠ³ΠΎΠ²ΠΎΠΉ ΠΏΠΎΠ»ΡΡΠΈΠ·Π°ΡΠΈΠ΅ΠΉ ΠΈ Π½Π΅Π½ΡΠ»Π΅Π²Π°Ρ Π΄Π»Ρ ΡΠ²Π΅ΡΠ° Ρ Π»Π΅Π²ΠΎΠΉ ΠΊΡΡΠ³ΠΎΠ²ΠΎΠΉ ΠΏΠΎΠ»ΡΡΠΈΠ·Π°ΡΠΈΠ΅ΠΉ. ΠΠΎΠ΄ΡΠ²Π΅ΡΠΆΠ΄Π΅Π½ΠΈΠ΅ΠΌ ΡΠΎΠ³ΠΎ, ΡΡΠΎ Π² ΠΏΠΎΡΠ»Π΅Π΄Π½Π΅ΠΌ ΡΠ»ΡΡΠ°Π΅ Π½Π° ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΡΠΈ ΡΡΡΠ΅ΡΡΠ²ΡΠ΅Ρ ΠΎΠ±ΡΠ°ΡΠ½ΡΠΉ ΠΏΠΎΡΠΎΠΊ ΡΠ½Π΅ΡΠ³ΠΈΠΈ, ΡΠ²Π»ΡΠ΅ΡΡΡ Π½Π°Π»ΠΈΡΠΈΠ΅ Π² ΡΠ΅Π½ΡΡΠ΅ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ½Π΅ΡΠ³ΠΈΠΈ ΡΠ»Π°Π±ΠΎΠ³ΠΎ Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ°ΠΊΡΠΈΠΌΡΠΌΠ° (ΠΏΡΡΠ½Π° ΠΡΠ°Π³ΠΎ), ΠΎΠ±ΡΡΡΠ½ΡΠ΅ΠΌΠΎΠ³ΠΎ Π΄ΠΈΡΡΠ°ΠΊΡΠΈΠ΅ΠΉ ΠΏΡΡΠΌΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ½Π΅ΡΠ³ΠΈΠΈ Π½Π° ΠΊΡΡΠ³Π΅ Π΄ΠΈΠ°ΠΌΠ΅ΡΡΠΎΠΌ 300 Π½ΠΌ (ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΠ΅Ρ Π΄ΠΈΠ°ΠΌΠ΅ΡΡΡ ΡΡΡΠ±ΠΊΠΈ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ½Π΅ΡΠ³ΠΈΠΈ). Π‘ΡΠ°Π²Π½ΠΈΠ²Π°Ρ ΡΠΈΡΠ»Π΅Π½Π½ΡΠ΅ ΠΈ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΠ΅ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ, Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΠΈΡΡ Π΄ΠΈΠ°ΠΌΠ΅ΡΡ ΡΡΡΠ±ΠΊΠΈ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° β ΠΎΠ½ ΡΠ°Π²Π΅Π½ ΡΠ°ΡΡΡΠΎΡΠ½ΠΈΡ ΠΌΠ΅ΠΆΠ΄Ρ Π½ΡΠ»ΡΠΌΠΈ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ. ΠΠ»Ρ ΡΠΈΡΠ»ΠΎΠ²ΠΎΠΉ Π°ΠΏΠ΅ΡΡΡΡΡ 0,95 ΠΈ Π΄Π»ΠΈΠ½Ρ Π²ΠΎΠ»Π½Ρ 532 Π½ΠΌ Π΄ΠΈΠ°ΠΌΠ΅ΡΡ ΡΡΡΠ±ΠΊΠΈ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ°Π²Π΅Π½ 300 Π½ΠΌ. Π’Π°ΠΊΠΆΠ΅ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΡΠΈ ΡΠΎΠΊΡΡΠΈΡΠΎΠ²ΠΊΠ΅ ΡΠΈΠ»ΠΈΠ½Π΄ΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²Π΅ΠΊΡΠΎΡΠ½ΠΎΠ³ΠΎ ΠΏΡΡΠΊΠ° Π²ΡΠΎΡΠΎΠ³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ° Π»ΠΈΠ½Π·ΠΎΠΉ Ρ ΡΠΈΡΠ»ΠΎΠ²ΠΎΠΉ Π°ΠΏΠ΅ΡΡΡΡΠΎΠΉ 0,95 Π²ΠΎΠ·Π½ΠΈΠΊΠ°Π΅Ρ ΠΎΡΠ΅ΡΠΈΠΌΠΌΠ΅ΡΡΠΈΡΠ½ΡΠΉ ΠΏΠΎΡΠΎΠΊ ΡΠ½Π΅ΡΠ³ΠΈΠΈ Ρ ΠΎΡΠ΅Π½Ρ ΡΠ»Π°Π±ΡΠΌ ΠΌΠ°ΠΊΡΠΈΠΌΡΠΌΠΎΠΌ Π² ΡΠ΅Π½ΡΡΠ΅ (ΠΏΡΡΠ½ΠΎ ΠΡΠ°Π³ΠΎ). Π’Π°ΠΊΠΎΠ΅ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΠΎΠ±ΡΡΡΠ½ΡΠ΅ΡΡΡ Π΄ΠΈΡΡΠ°ΠΊΡΠΈΠ΅ΠΉ ΠΏΡΡΠΌΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ½Π΅ΡΠ³ΠΈΠΈ Π½Π° ΠΊΡΡΠ³Π»ΠΎΠΉ ΠΎΠ±Π»Π°ΡΡΠΈ Π΄ΠΈΠ°ΠΌΠ΅ΡΡΠΎΠΌ 300 Π½ΠΌ, Π² ΠΊΠΎΡΠΎΡΠΎΠΉ ΠΏΠΎΡΠΎΠΊ ΡΠ½Π΅ΡΠ³ΠΈΠΈ ΠΎΠ±ΡΠ°ΡΠ½ΡΠΉ. ΠΡΠΎ ΡΠ°ΠΊΠΆΠ΅ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΠΎΠ΄ΡΠ²Π΅ΡΠΆΠ΄Π΅Π½ΠΈΠ΅ΠΌ ΠΏΡΠΈΡΡΡΡΡΠ²ΠΈΡ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° ΡΠ½Π΅ΡΠ³ΠΈΠΈ Π½Π° ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΡΠΈ.
Using two identical microobjectives with a numerical aperture NA = 0.95, we experimentally demonstrate that the on-axis intensity near the tight focal spot of an optical vortex with a topological charge 2 is zero for right-handed circular polarization and nonzero for left-handed circular polarization. This serves to confirm that in the latter case there is a reverse energy flow on the optical axis, as testified by a very weak local maximum (the Arago spot) detected at the center of the measured energy flow distribution, caused by diffraction of the direct energy flow by a 300 nm circle (the diameter of a reverse energy flow tube). The comparison of numerical and experimental intensity distributions shows that it is possible to determine the diameter of the reverse energy flow "tube", which is equal to the distance between the adjacent intensity nulls. For NA = 0.95 and a 532 nm incident wavelength, the diameter of the on-axis reverse energy flow "tube" is measured to be 300 nm. It is also experimentally shown that when an optical beam with second-order cylindrical polarization is focused with a lens with NA = 0.95, there is a circularly symmetric energy flow in the focus with a very weak maximum in the center (the Arago spot), whose distribution is determined by diffraction of the direct energy flow by a 300 nm circular region, where the energy flow is reverse. This also confirms that in this case, there is a reverse energy flow on the optical axis.Π Π°Π±ΠΎΡΠ° Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΏΡΠΈ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠ΅ Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ Π½Π°ΡΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° (Π³ΡΠ°Π½Ρ 18-19-00595) Π² ΡΠ°ΡΡΠΈ Β«ΠΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½Ρ ΠΏΠΎ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° Π² ΡΠΎΠΊΡΡΠ΅ ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²ΠΈΡ
ΡΡ Ρ ΠΊΡΡΠ³ΠΎΠ²ΠΎΠΉ ΠΏΠΎΠ»ΡΡΠΈΠ·Π°ΡΠΈΠ΅ΠΉΒ», Π ΠΎΡΡΠΈΠΉΡΠΊΠΎΠ³ΠΎ ΡΠΎΠ½Π΄Π° ΡΡΠ½Π΄Π°ΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ (Π³ΡΠ°Π½Ρ 18-29-20003) Π² ΡΠ°ΡΡΠΈ Β«ΠΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½Ρ ΠΏΠΎ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° Π² ΡΠΎΠΊΡΡΠ΅ ΠΏΠΎΠ»ΡΡΠΈΠ·Π°ΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ Π²ΠΈΡ
ΡΡ Π²ΡΠΎΡΠΎΠ³ΠΎ ΠΏΠΎΡΡΠ΄ΠΊΠ°Β» ΠΈ ΠΠΈΠ½ΠΈΡΡΠ΅ΡΡΡΠ²Π° Π½Π°ΡΠΊΠΈ ΠΈ Π²ΡΡΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π Π€ Π² ΡΠ°ΠΌΠΊΠ°Ρ
Π²ΡΠΏΠΎΠ»Π½Π΅Π½ΠΈΡ ΡΠ°Π±ΠΎΡ ΠΏΠΎ ΠΠΎΡΡΠ΄Π°ΡΡΡΠ²Π΅Π½Π½ΠΎΠΌΡ Π·Π°Π΄Π°Π½ΠΈΡ Π€ΠΠΠ¦ Β«ΠΡΠΈΡΡΠ°Π»Π»ΠΎΠ³ΡΠ°ΡΠΈΡ ΠΈ ΡΠΎΡΠΎΠ½ΠΈΠΊΠ°Β» Π ΠΠ (ΡΠΎΠ³Π»Π°ΡΠ΅Π½ΠΈΠ΅ 007-ΠΠ/Π§3363/26) Π² ΡΠ°ΡΡΠΈ Β«Π‘ΠΈΠ»Ρ, Π΄Π΅ΠΉΡΡΠ²ΡΡΡΠΈΠ΅ Π½Π° Π½Π°Π½ΠΎΡΠ°ΡΡΠΈΡΡ Π² ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠΌ ΠΏΠΎΡΠΎΠΊΠ΅ ΡΠ½Π΅ΡΠ³ΠΈΠΈΒ»
The Dependence of the Superconducting Transition Temperature of Organic Molecular Crystals on Intrinsically Non-Magnetic Disorder: a Signature of either Unconventional Superconductivity or Novel Local Magnetic Moment Formation
We give a theoretical analysis of published experimental studies of the
effects of impurities and disorder on the superconducting transition
temperature, T_c, of the organic molecular crystals kappa-ET_2X and beta-ET_2X
(where ET is bis(ethylenedithio)tetrathiafulvalene and X is an anion eg I_3).
The Abrikosov-Gorkov (AG) formula describes the suppression of T_c both by
magnetic impurities in singlet superconductors, including s-wave
superconductors and by non-magnetic impurities in a non-s-wave superconductor.
We show that various sources of disorder lead to the suppression of T_c as
described by the AG formula. This is confirmed by the excellent fit to the
data, the fact that these materials are in the clean limit and the excellent
agreement between the value of the interlayer hopping integral, t_perp,
calculated from this fit and the value of t_perp found from angular-dependant
magnetoresistance and quantum oscillation experiments. If the disorder is, as
seems most likely, non-magnetic then the pairing state cannot be s-wave. We
show that the cooling rate dependence of the magnetisation is inconsistent with
paramagnetic impurities. Triplet pairing is ruled out by several experiments.
If the disorder is non-magnetic then this implies that l>=2, in which case
Occam's razor suggests that d-wave pairing is realised. Given the proximity of
these materials to an antiferromagnetic Mott transition, it is possible that
the disorder leads to the formation of local magnetic moments via some novel
mechanism. Thus we conclude that either kappa-ET_2X and beta-ET_2X are d-wave
superconductors or else they display a novel mechanism for the formation of
localised moments. We suggest systematic experiments to differentiate between
these scenarios.Comment: 18 pages, 5 figure
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