Факультет комп’ютерних наук
Постійне посилання на розділhttps://ekhnuir.karazin.ua/handle/123456789/47
Переглянути
7 результатів
Результати пошуку
Документ Semiclassic models of the dissipative regime of instability and superradiation of a quantum radiator system(2021) Kuklin, V.M.; Lazurik, V.T.; Poklonskiy, E.V.; Куклін, В.М.; Лазурик, В.Т.; Поклонский, Є.В.The paper discusses the similarity between dissipative generation and superradiance regimes for systems of excited quantum emitters placed in an open cavity. In the case of the existence of a resonator field due to reflections from the ends of the system, a dissipative generation regime is usually realized. In this case, the decrement of oscillations in the waveguide in the absence of radiators turns out to be greater than the increment of the arising instability of the system of radiators placed in the resonator. When describing this mode, the influence of the emitters on each other and the sum of their own fields is neglected. The resonator field forces the oscillators to emit or absorb quanta synchronously with it, depending on the local value of the population inversion. Lasing takes on a weakly oscillatory character due to an asynchronous change in the population inversion of the system of emitting dipoles (nutations), which have a ground and excited energy levels. To describe the process, the equations of the semiclassical theory based on the use of the density matrix are quite sufficient. In the case when there is no resonator or waveguide field, taking into account the eigenfields of the oscillators becomes essential. To simulate the superradiance process, large emitting particles are used, to describe which one should use the equations for the density matrix. It is shown that the interaction of quantum emitters in this case is due to electromagnetic fields under conditions when the overlap of their wave functions is insignificant. Equations are obtained that allow considering the process of interaction of emitters. When the emitters interact, an integral field is formed in the resonator, an increase in the intensity of which leads to synchronization of the emitters. It is shown that the characteristic times of the development of the process, as well as the attainable amplitudes of the excited fields for dissipative regimes of generation and regimes of superradiance of emitters filling an open resonator, are comparable.Документ Dissipative instabilities and superradiation regimes (classic models)(2021) Kuklin, V.M.; Poklonskiy, E.V.; Куклін, Володимир Михайлович; Поклонський, Євген ВасильовичThe generation of an electromagnetic field by oscillators in an open resonator is discussed in a one-dimensional approximation. In this case, the development of the so-called dissipative instability the dissipative generation regime. Such an instability with the generation of electromagnetic oscillations arises when the decrement of oscillations in an open resonator in the absence of oscillators turns out to be greater than the increment of the resulting instability of the system of oscillators placed in this resonator. It is assumed that the oscillators do not interact with each other, and only the resonator field affects their behavior. If the resonator field is absent or small, the superradiance regime is possible, when the radiation of each oscillator is essential and the field in the system is the sum of all the eigenfields of the oscillators. In the dissipative regime of instability generation, the system of oscillators is synchronized by the induced resonator field. The synchronization of the oscillators in the superradiance mode owes its existence to the integral field of the entire system of oscillators. With a weak nonlinearity of the oscillators, a small initiating external field is required to excite the generation regime. It is noteworthy that the maximum value of the superradiance field is approximately two times less than the maximum field that the same particles could generate if they were at the same point. In all cases, for a given open resonator, the superradiance field turned out to be somewhat larger than the resonator field. Nevertheless, for the same resonator, the increments and attainable field amplitudes in both cases are of the same order of magnitude.Документ Arguments in Favour of Economic Liberalization(2020) Bakirov, V.S.; Kostenko, E.; Kuklin, V.M.The article illustrates the results of the economic development of the first fifteen years of the XXI century under the conditions of unprecedented economic freedom, globalization and the appearance of new informational sectors up to and including the first attempts at revising liberalism. The analysis of statistical data demonstrates an obvious increase in the percentage of well-off people in many countries as well as the increased economic capabilities of small, medium and large businesses, whose assets are distributed among an ever-increasing number of owners. This provides the impetus to review our collective approach to liberalization and globalization, as well as to view its unexpected strong sides that make human progress possible.Документ On the periodic change of the luminosity of the cosmic sources with an active medium(2020) Kostenko, V.V.; Kuklin, V.M.; Poklonskiy, E.V.; Костенко, В.В.; Куклін, В.М.; Поклонський, Є.В.The presence of an internal layer with an active medium in a hot radiation source is considered, which can be described by a quantum two-level system located near equilibrium. The population of the upper and lower levels is approximately equal. It is shown that during convection from deeper hot layers, which supports the inversion of the populations of the active system, generation of induced radiation pulses is possible, the intensity of which is comparable to or greater than the intensity of the background spontaneous radiation of the source. With a sufficient thickness of the surface layers due to the effects of radiation scattering in them, the emission spectrum of a completely black body may well form there. Pulse generation near a previously detected new threshold of induced radiation can lead to a periodic change in the radiation intensity of the source as a whole. This threshold is determined by the equality of the squared population inversion to the total number of states. The generation of pulses of induced radiation is considered both in Einstein's representation, on the basis of balanced equations, and using a semiclassical description for small values of population inversion and for low levels of electric field intensity, when the Rabi frequency is less than the line width. The description of the induced radiation process is reduced to a one-parameter system of equations. Periodic solutions are represented by closed trajectories on the phase plane (relative density of quanta, relative density of population inversion). A similar layer with an active medium, which can be described by a quantum two-level system located near equilibrium, can exist in stars and is most likely localized in the photosphere. If there is significant convection in the star’s atmosphere, conditions can be realized for generating pulses of induced radiation. It turns out that one can see the similarity of the obtained solutions with known observations of changes in the luminosity of Cepheid stars (Cepheus delta and the North Star).Документ Selected chapters (theoretical physics)(Kharkiv : V.N. Karazin Kharkiv National University, 2021) Kuklin, V.M.; Куклин, Владимир Михайлович; Куклін, Володимир МихайловичThe book considers spontaneous and induced emission of particles and waves. The formation of coherent pulses near a detected new threshold of induced radiation is discussed. It is shown how modulation instabilities generate self-similar structures and anomalous waves. A comparison is made of the dynamics of instability of Langmuir oscillations in plasma and heating of ions in Silin and Zakharov models. Turbulent-wave instability is discussed and a new approach to the description of the Mossbauer effect is presented. The similarity of processes of superradiation and dissipative instability is noted. Structural transitions in the convective layer and the appearance of large-scale vortices during modulation instability of developed convection and other relevant problems are discussed. It is of interest to specialists, graduate students and students of physics departments.Документ Скользкие ступени эволюции : в 2 ч. Ч. 2. Плавильный котел Европы(Харьков : Харьковский национальный университет имени В.Н. Каразина, 2020) Куклин, Владимир Михайлович; Куклін, Володимир Михайлович; Kuklin, V.M.В книге представлен современный взгляд на экономическое, социальное, религиозное, этическое и технологическое развитие общества и рассмотрена эволюция в основном крупных государств Европы с начала XIV до конца XX вв. Обсуждается природа социальных изменений, революционных процессов и мотивы их участников. Значительное внимание уделяется развитию культуры и искусства в период эпохи Возрождения и позднее. Рассмотрено формирование института науки и обсуждаются основные тенденции научных исследований, а также технологических разработок. Уделено внимание экономическим и политическим предпосылкам множества военных конфликтов, причинам взлета, ослабления и разрушения крупных империй. Анализируется природа экономического роста и упадка разных стран. Рассмотрено формирование границ государств Европы. Представляет интерес для читателей, изучающих процессы развития общества.Документ Избранные главы (теоретическая физика)(Харьков: ХНУ имени В.Н. Каразина, 2021) Куклин, В.М.; Kuklin, V.M.; Куклін, В.М.