Semiclassic Models of the Dissipative Regime of Instability and Superradiation of a Quantum Radiator System

East European Journal of Physics ◽

10.26565/2312-4334-2021-2-06 ◽

2021 ◽

Keyword(s):

Density Matrix ◽

Population Inversion ◽

Open Resonator ◽

Energy Levels ◽

System A ◽

Oscillatory Character ◽

Radiator System ◽

Integral Field ◽

Local Value ◽

Quantum Emitters

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.

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ON THE NATURE OF COHERENTS IN THE SYSTEM OF OSCILLATORS

10.46813/2019-122-091 ◽

2019 ◽

pp. 91-95

Author(s):

V.M. Kuklin

Keyword(s):

Spatial Variation ◽

Quantum System ◽

Field Intensity ◽

Radiation Intensity ◽

Population Inversion ◽

Classical Case ◽

Radiation Energy ◽

Dispersion Characteristics ◽

Quantum Analogue ◽

Integral Field

The paper presents the transition to the regime of induced radiation of a system of oscillators in the classical and the quantum cases. This transition occurs due to synchronization by the integral field of the phases of a small part of oscillator-emitters. In the quantum analogue of this model, it is shown that the formation of an induced (and, therefore, coherent, as noted by Ch. Towns) pulse of the field is due to the interference of nutation of population inversion in different regions of the system of oscillators. The law of spatial variation of the field intensity is deter-mined by the dispersion characteristics of the system and the level of absorption or output of the radiation energy. Only a small fraction of oscillators provide induced radiation: 8% in the classical case and half as much in the case of a quantum system, where a change in the sign of population inversion in the regions of the highest field values significantly affects the limitation of the radiation intensity.

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H2O Maser Pumping by Shock Waves

Symposium - International Astronomical Union ◽

10.1017/s0074180900090100 ◽

1992 ◽

Vol 150 ◽

pp. 245-247

Author(s):

Jacques R.D. Lepine ◽

Astrid Heske

Keyword(s):

Shock Wave ◽

Shock Waves ◽

Population Inversion ◽

Energy Levels ◽

Rotational Energy ◽

Molecular Gas ◽

Cooling Process ◽

Final Cool

We discuss a simple H2O maser pumping mechanism in which the population inversion of the masing levels takes place during the quick cooling of the gas behind a shock wave. The population of the rotational energy levels in the initial hot state and final cool state of the molecular gas, and the decay paths between levels are analysed to calculate the average number of 22 GHz photons emitted per H2O molecule in the cooling process.

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Quantum information aspects on bulk and nano interacting Fermi system: A spin-space density matrix approach

Physics Letters A ◽

10.1016/j.physleta.2016.08.003 ◽

2016 ◽

Vol 380 (41) ◽

pp. 3394-3403 ◽

Cited By ~ 1

Author(s):

R. Afzali ◽

N. Ebrahimian ◽

B. Eghbalifar

Keyword(s):

Quantum Information ◽

Density Matrix ◽

Fermi System ◽

Matrix Approach ◽

Spin Space ◽

Space Density ◽

System A

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Influence of Hygrothermal Environmental Conditions on the Vibratory Responses of Glass Polyester Composite Plate Impacted by a Steel Projectile

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.28.8 ◽

2017 ◽

Vol 28 ◽

pp. 8-20

Author(s):

Amine Bakhti ◽

Farouk Benallel Boukhoulda

Keyword(s):

Contact Force ◽

Energy Levels ◽

Composite Plates ◽

Mechanical Responses ◽

System A ◽

Resonance Frequencies ◽

Polyester Composite ◽

The Impact ◽

Aged Composite

The objective of the present work is an analysis of vibratory responses due to the impact of projectile in steel against a glass/polyester composite material under hygrothermal conditions with different energy levels. In the first part of this study, by means of a data acquisition system, a signal processing analysis of the contact force and acceleration of the projectile is carried out in order to deduce the oscillations of the responses. These are generated by the vibrations induced by the contact between the plate and the impactor. The analysis of the vibrations by the calculation of the Fast Fourier Transform (FFT) applied to the oscillations of the contact force allows to defining the resonance frequencies of the plate for the different energy levels. The measure of the Frequency Response Functions (FRF) from the obtained responses allows the determination of the damping of the impacted composite material.In the second part of this study highlights quantitatively and puts into evidence the influence of hygrothermal conditions on the mechanical responses such as contact force, acceleration, frequency and damping of aged and non-aged composite plates.

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NMAGIC: Fast Parallel Implementation of a χ2-Made-To-Measure Algorithm for Modeling Observational Data

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306005266 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 91-91

Author(s):

Flavio De Lorenzi ◽

Victor P. Debattista ◽

Ortwin Gerhard ◽

Niranjan Sambhus

Keyword(s):

Distribution Function ◽

Observational Data ◽

Parallel Implementation ◽

Difficult Problem ◽

Target System ◽

Great Promise ◽

Spherical System ◽

System A ◽

And Performance ◽

Integral Field

We describe a made-to-measure algorithm (χ2M2M) for constructing N-particle models of stellar systems from observational data (De Lorenzi Debattista, Gerhard, et al. (2007)), extending earlier ideas by Syer & Tremaine (1996). The algorithm properly accounts for observational errors. We implemented this algorithm in a parallel code NMAGIC and carried out a sequence of tests to illustrate its power and performance: (i) We reconstructed an isotropic Hernquist (1990) model from density moments and projected kinematics including higher-order Gauss-Hermite moments (Gerhard (1993), van der Marel & Franx (1993)). We gave NMAGIC two initial models, made from distribution function (Debattista & Sellwood (2000)), with different density distributions to start with. While both recovered the correct differential energy distribution and intrinsic kinematics, that with density closer to the density of the final model had smaller final deviations from the target observables, and a narrower distribution of weights. (ii) We built a self-consistent oblate three-integral maximum rotator model and compared how the distribution function is recovered from integral field and slit kinematic data. In these experiments we gave the algorithm a difficult problem to solve. Since the target system was maximally rotating, the weights of all counter-rotating particles were zero. Using density observables and either slit or integral field kinematics, NMAGIC was asked to recover this maximally rotating model starting from an isotropic spherical system. A good fit to the kinematic constraint data was achieved. These experiments also showed the advantage of integral field data over slit data for constraining the model. The different applications show that the χ2M2M algorithm is practical, reliable and can be applied to various systems. High quality dynamical models of galaxies can be achieved which match targets to ~1σ for plausible uncertainties in the observables, and without symmetry restrictions. We conclude that χ2M2M holds great promise for unraveling the nature of galaxies.

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Conditions for Population of Energy Levels Inversion when Active Medium Based on Gadolinium Isotopes Gd155 and Gd156 Couple Neutron Pumping

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.16-18.055-062 ◽

2018 ◽

pp. 55-62

Author(s):

I. V. Shamanin ◽

M. A. Kazaryan

Keyword(s):

Neutron Flux ◽

Neutron Scattering ◽

Active Medium ◽

Isomeric State ◽

Neutron Capture ◽

Population Inversion ◽

Energy Levels ◽

Radiative Neutron ◽

Radiative Neutron Capture ◽

Isomeric States

The paper theoretically studies the possibility of energy transformation of fast and epithermal neutrons to energy of coherent photon radiation at the expense of a neutron pumping of the active medium formed by nucleus with longliving isomerous states. The channel of the nucleus formation in isomeric state as a daughter nucleus resulting from the nuclear reaction of neutron capture by a lighter nucleus is taken into consideration for the first time. Assessment of neutron flux spectrum parameters providing transition from the main state into one of the excited ones for the nuclei of isotopes54Xe130,10Ne22is made. It was shown that to transit the isotope nuclei into the excited state by forward neutron scattering on the nuclei it is necessary to “select” the isotopes not only with great specific energy of nucleons coupling but also with a small value of the neutron absorption cross section. Moreover, the paper performs the analysis of cross sections dependence of radiative neutron capture by the nuclei of gadolinium isotopes Gd155and Gd156. As a result, the speed of Gd156nuclei formation is stated to exceed the speed of their “burnup” in the neutron flux. It is provided by a unique combination of absorbing properties of two isotopes of gadolinium Gd155 and Gd156 in both thermal and resonance regions of neutron energy. We have formulated the conditions required for making isotope nuclei excited by forward neutron scattering on nuclei and for storing nuclei in excited states. The relation which allows estimating processes parameters of neutron capture by nuclei, formation and decay of nuclei isomeric states is obtained as a result of analytical solution of differential equations system of nuclide kinetics taking into account the decay of nuclei isomeric states. The paper makes the possibility analysis of neutron pumping of the participating medium created by the hafnium isotope nuclei. The properties of hafnium isotopes nuclei is found to do not allow providing conditions for population inversion of energy levels due to the formation of hafnium nuclei in isomeric state Hf178m2in the neutron flux. The paper shows the possibility of excess energy accumulation in the participating medium created by the nuclei of the pair of gadolinium isotopes Gd155and Gd156due to formation and storage of nuclei in isomeric state at radiative neutron capture by the nuclei of the stable isotope with a smaller mass. It is concluded that when the active medium created by gadolinium nuclei is pumped by neutrons with the flux density of the order of 1013cm-2·s-1, the condition of levels population inversion can be achieved in a few tens of seconds. The wave length of the radiation generated by the medium is 0.0006 nm. Sintered ceramics Gd2O3based on enriched in the 155-th isotope of gadolinium can be considered a possible active medium. Thus, there is a possibility of creation of the laser techniques of new generation with the parameters providing its application in pulse power engineering of the future.

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Population inversion in a multilevel system: a model study

The Journal of Physical Chemistry ◽

10.1021/j100125a015 ◽

1993 ◽

Vol 97 (23) ◽

pp. 6175-6183 ◽

Cited By ~ 16

Author(s):

Bjarne Amstrup ◽

Andras Lorincz ◽

Stuart A. Rice

Keyword(s):

Population Inversion ◽

Multilevel System ◽

System A ◽

Model Study

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Possible new interstellar masers

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1980.0148 ◽

1980 ◽

Vol 373 (1753) ◽

pp. 269-284 ◽

Cited By ~ 5

Keyword(s):

Population Inversion ◽

Diatomic Molecules ◽

Energy Levels ◽

Rotational Energy ◽

Stimulated Emission

A collisional mechanism for the production of population inversion in the Λ -doublet sub-levels of the lowest rotational energy levels of diatomic molecules is considered. This leads to the conclusion that not only should the known celestial masers, OH and CH, be capable of exhibiting stimulated emission, but also H F + , HC1 + and SH.

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