(b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

The Quantum Theory of Light

Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

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Plasma-liquid interactions: A review and roadmap

Cyclostationarity: half a century of research

Journal of Applied physics,Vol.33 : 1962年に発表されたレオロジー関連の論文

There can be little doubt that the Monte Carlo method for semiconductor device simulation has enormous power as a research tool. It represents a detailed physical model of the semiconductor material(s), and provides a high degree of insight into the microscopic transport processes. However, if the authority ascribed to Monte Carlo models of devices at 1/spl mu/m feature size is to be maintained for devices below O.1/spl mu/m, modelling of the fundamental physics must be further improved. And if the Monte Carlo method is to be successful as a semiconductor device design tool, the device model must be made more realistic. Success in the industrial sector depends on this, but also on achieving fast run-times optimisation - where the scope and need for ingenuity is now greatest.

The Monte Carlo method for semiconductor device simulation

Kinetic and hydrodynamic models for simulation of carrier heating and transport in bulk semiconductors and semiconductor devices are considered. In the framework of the kinetic approach based on the single-particle Monte Carlo simulation main attention is paid to the hydrodynamic model parameters as well as to the time- and frequency-dependences of the hot carrier linear response calculations. In the framework of the hydrodynamic approach the drift velocity and mean energy conservation equations are investigated under the single electron gas approximation. Possible extensions as well as widely used simplifications of this model such as the energy transport model, the local energy model, the extended drift-diffusion formalism and the drift-diffusion approximation are considered.

Conservation equations for hot carriers—I. Transport models

We propose an analytical model for the high-frequency noise of Schottky-barrier diodes (SBD). The high-frequency spectrum is shown to be governed by collective motions of carriers in the neutral region of the SBD caused by the self-consistent electric field. The model is validated by comparison with Monte Carlo simulations of GaAs SBDs operating from barrier-limited to flatband conditions.

Analytical model of high-frequency noise spectrum in Schottky-barrier diodes

Small-signal analysis of the Boltzmann equation from harmonic- and impulse-response methods.

The high-frequency generation associated with the optical-phonon transit-time resonance in a constant electric field is analyzed by Monte Carlo simulations of different nitrides such as InN, GaN and AlN. Calculations show that the microwave power generation occurs in a wide frequency range covering practically the whole submillimeter range and persisting in the THz frequency range up to the liquid nitrogen temperature.

Monte Carlo calculations of THz generation in wide gap semiconductors

A hydrodynamic approach based on velocity and energy conservation equations is developed and used for the simultaneous evaluation of the electronic steady-state transport, small-signal response and noise in an Si structure. An original decomposition of velocity and energy profiles along the structure in terms of field, convective and diffusion contributions is presented. The local distribution of the noise source and voltage spectral density is carried out within the transfer-impedance method. The excellent agreement of the approach thus developed with Monte Carlo simulations supports its physical reliability and effectiveness for submicron-device modelling.

Pavel Shiktorov

Papers

Conservation equations for hot carriers—I. Transport models

Analytical model of high-frequency noise spectrum in Schottky-barrier diodes

Small-signal analysis of the Boltzmann equation from harmonic- and impulse-response methods.

Monte Carlo calculations of THz generation in wide gap semiconductors

Hydrodynamic and Monte Carlo simulation of steady-state transport and noise in submicrometre silicon structures