- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Introduction to Quantum Electronics and Nonlinear Optics || Field Interaction with a??Free Chargesa??
摘要： The chapter discusses the interaction of electromagnetic fields with 'free charges' in plasma, focusing on the kinetic equation, cyclotron resonance, and fundamental absorption in semiconductors. It explores the classical and quantum mechanical descriptions of plasma behavior under external fields, including the effects of magnetic fields on electron motion and the absorption of electromagnetic waves by semiconductors.
关键词： semiconductors,plasma,cyclotron resonance,electromagnetic fields,free charges,kinetic equation,fundamental absorption
更新于2025-09-23 15:19:57
-
Electron-positron pair production in frequency modulated laser fields
摘要： The momentum spectrum and the number density of created electron-positron pairs in a frequency modulated laser field are investigated using the quantum kinetic equation. It is found that the momentum spectrum presents an obvious interference pattern. This is an imprint of the frequency modulated field on the momentum spectrum, because the momentum peaks correspond to the pair production process by absorbing different frequency component photons. Moreover, the interference effect can also be understood qualitatively by analyzing turning-point structures. The study of the pair number density shows that the number density is very sensitive to modulation parameters and can be enhanced by 2 or 3 orders of magnitude for certain modulation parameters, which may provide a new way to increase the number of created electron-positron pairs in future experiments.
关键词： number density,quantum kinetic equation,electron-positron pair production,frequency modulated laser fields,momentum spectrum
更新于2025-09-16 10:30:52
-
Evaluation of a spectral line width for the Phillips spectrum by means of numerical simulation
摘要： The work aims to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the situations described by the Phillips spectrum. We evaluate a spectral line width of the spectrum from the simulations in the framework of primordial dynamical equations at different levels of nonlinearity in the system, corresponding to the weakly turbulent Kolmogorov–Zakharov spectra ω?4, Phillips spectra ω?5, and intermediate cases. The original motivation of the work was to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the Phillips spectrum. It is shown that, even in the case of relatively high average steepness, when the Phillips spectrum is present in the system, the spectral lines are still very narrow, at least in the region of the direct cascade spectrum. It allows us to state that, even in the case of the Phillips spectrum, one of the assumptions used for the derivation of the Hasselmann kinetic equation is still valid, at least in the case of moderate whitecapping.
关键词： numerical simulation,water waves,Phillips spectrum,spectral line width,kinetic equation
更新于2025-09-10 09:29:36
-
Theoretical Investigation of the Shubnikov-de Haas Magnetoresistance Oscillations in a Quantum well under the Influence of Confined Acoustic Phonons
摘要： The Shubnikov – de Haas magnetoresistance oscillations in the Quantum well (QW) under the influence of confined acoustic phonons, The theoretical results show that the conductivity tensor, the complex magnetic impedance of the magnetic field, the frequency, the amplitude of the laser radiation, the QW width, the temperature of the system and especially the quantum index m characterizes the confinement of the phonon. The amplitude of the oscillations of the Shubnikov-de Haas impedance decreases with the increase of the influence of the confined acoustic phonons. The results for bulk phonons in a QW could be achieved, when m goes to zero. We has been compared with other studies when perform the numerical calculations are also achieved for the GaAs/AlGaAs in the QW. Results show that The Shubnikov – de Haas magnetoresistance oscillations amplitude decrease when phonon confinement effect increasing and when width L of the QW increases to a certain value, The Shubnikov – de Haas magnetoresistance oscillations amplitude completely disappears can not be observed.
关键词： Quantum well and width L of quantum well,Confined acoustic phonons,Quantum kinetic equation,Laser radiation,Shubnikov–de Haas magnetoresistance oscillations
更新于2025-09-10 09:29:36
-
Interaction of External Acoustic Waves - Confined Electrons - Internal Phonons in a Cylindrical Quantum Wire with an Infinite Potential in the Presence of an External Magnetic Field
摘要： Interaction of external acoustic waves - confined electrons - internal phonons in a cylindrical quantum wire with an infinite potential (CQWIP) has been theoretically studied via the quantum kinetic equation for electrons in the presence of an external magnetic field (EMF). The quantum kinetic equation for the distribution function of electrons interacting with internal and external acoustic phonons is obtained from the Heisenberg equation of motion and the model of CQWIP. The density of acoustomagnetoelectric (AME) current and the analytical expressions for the AME field in the CQWIP in the presence of the EMF are obtained. The theoretical results are numerically evaluated for the specific CQWIP of GaAs/GaAsAl. It is shown that the AME field strongly depends on the system temperature in both cases of the strong magnetic field and the weak magnetic field. However, the graph showing the relationship between the AME field and the system temperature has the peaks in case of the strong magnetic field. The reason may be due to movement of the electrons between the mini-bands. The AME field obtained in this work are then compared with those of bulk semiconductors, superlattices, quantum wells (QW) and rectangular quantum wire (RQW).
关键词： Cylindrical quantum wire,Acoustomagnetoelectric field,Kinetic equation method
更新于2025-09-10 09:29:36
-
Theoretical Study of the Magneto-Thermoelectric Effect in Doped Semiconductor Superlattices under the Influence of an Electromagnetic Wave by Using a Quantum Kinetic Equation
摘要： By using a quantum kinetic equation for electrons, we studied magneto - thermoelectric effects in the doped semiconductor superlattice (DSSL) under the influence of electromagnetic waves (EMW). In case of the electron - acoustic phonon interaction, we have also figured out analytical expressions of the Ettingshausen coefficient (EC) in DSSL. These expressions are quite different from those which were obtained in the case of bulk semiconductors. The results are numerically calculated for the GaAs:Be/ GaAs:Si DSSL; we found that the EC depends on the characteristic parameters of EMW, temperature and the characteristic parameters of DSSL. The results are consistent with recently experimental observations but the EC is different from that in the bulk semiconductors or bismuth. In addition, the impact of the EMW on the Ettingshausen effect was also discovered. These are latest results which have been studied in terms of Ettingshausen effect in DSSL.
关键词： Semiconductor Superlattices,Doped Superlattices,Acoustomagnetoelectric field,Kinetic equation method
更新于2025-09-10 09:29:36