Arbitrary Energy Level Research Articles

Gases bosônicos armadilhados

O espectro dos modos coerentes para gás atômico de Bose diluído, confinado em uma armadilha harmônica não isotrópica é determinado e utiliza-se da teoria de perturbação otimizada e a técnica das raízes aproximantes auto-similares. As expressões obtidas são válidas para níveis de energia arbitrários de todos os modos coerentes excitados. Este artigo deve ser utilizado como ponto de início para os alunos que querem se aprofundar no tema de condensação de Bose-Einstein atualmente presente em quase todos periódicos de Física.

N-P pairing in nuclei

Variational wavefunctions for treating N-P pairing in the T=1 and T=0 channels are presented. Alpha-like correlations are explicitly included in the wavefunctions and arbitrary single-particle energy level spacings are allowed. A triple projection before variation procedure is used to obtain these wavefunctions. Taking a model system with equally spaced single-particle levels, several features of nuclei near the N=Z line are calculated. A new type of multiple degeneracy is found in nuclei near the N=Z line.

Semiclassical approach to resonance-optics polarization effects in coherent and squeezed fields

Equations are derived for the atomic density matrix and relaxation operator for a broadband squeezed field in an arbitrary polarization state and resonance atomic energy levels with an arbitrary degree of degeneracy. It is shown that suppression of the relaxation of the quadrature component of the atomic polarization depends strongly on the type of resonance transition and the polarization state of the squeezed and coherent perturbing fields. When the resonance levels are strongly degenerate, the relaxation of the quadrature component of the atomic polarization under conditions of maximum suppression is nonexponential in character. The mathematical apparatus developed here makes it possible to calculate polarization-related aspects of the multifrequency optical behavior of atomic and molecular systems resonantly excited both by coherent light and by broadband squeezed fields.

On tunnelling in the cubic potential

The tunnelling rate in real time in the semiclassical limit has been calculated for arbitrary energy levels in the cubic potential. For the ground state it agrees well with the result found by the instanton method.

A formula for energy displacements for the confined hydrogen atom

A simple approximate formula giving the first deviation from an arbitrary Coulomb energy level due to the presence of a spherical confining boundary is derived. It is shown that the Coulomb degeneracy is broken so that the state of lowest angular momentum is raised the highest in energy.

Theoretical analysis of resonant tunneling through finite superlattices

AbstractA theoretical study has been carried out with a view to understanding the resonant tunneling phenomena in superlattice structures. For a general potential distribution, the resonance condition is derived and the relationship is found between the resonance levels and the subbands in an infinite superlattice. Especially, the relationship is studied between the resonance characteristics of a unit superlattice section with an arbitrary potential distribution and those of an n‐period superlattice made of n stages of unit superlattices. It is found that the discriminating function of the n‐period superlattice is given by a Chebyshev polynomial of that of the unit section. Hence, if any potential distribution (including an asymmetric one) is repeated at least twice, a resonance level can always be generated in each subband (with a zero bias voltage). A method based on this fact is presented for generating a resonance at an arbitrary energy level in an n‐period superlattice. Further, by way of these discussions, it is pointed out that there exist higher‐order resonances. An example for this phenomenon is presented.

On occupation functions of donor- and acceptor-like interface states in metal-insulator-semiconductor tunnel structures

This paper presents a theoretical study on the occupation functions of interface states in MIS tunnel structures. Based on Shockley-Read-Hall (SRH) statistics and considering carriers tunneling between the metal and interface states, occupation functions of both donor- and acceptor-like interface states at arbitrary energy level within the semiconductor band gap are derived and analyzed. It reveals that, for the same energy level, the occupation functions of donor-like and acceptor-like interface states are remarkably different in magnitude. The deviation in occupation functions of these two types of interface states is a nonlinear function of the ratio of capture cross-section of the charge states to that of the neutral states ( C C/ C N) and the semiconductor surface conditions. If the insulating layer (SiO 2) is relatively thick (> 50 Å) or thin (< 10 Å), interface states are in equilibrium with the semiconductor or the metal, respectively. Under the circumstances, the occupation functions of the two types of interface states are no longer distinguishable. Alternatively, they can be approximated by the well-known Fermi-Dirac distribution function. In this paper, quantitative influences of key parameters of MIS tunnel structures such as insulating layer thickness, electron and hole density at the semiconductor surface, capture cross-sections for charged and neutral states, etc., on interface states occupation function are discussed. For Gaussian-distributed donor- and acceptor-like interface states, the quantitative roles of interface states in charge storage and current-assisting effects are also demonstrated.

Representation of the excited energy levels of quantum systems via the functional integrals

It is shown that an arbitrary excited energy level of a quantum system can be represented in the compact form via the functional integrals. The well-known formulae for the ground state energy are generalized, thus enlarging the application area of the functional integrals in quantum mechanics.

A statistical derivation of the density of final states for the exciton model

A new method for the derivation of the density of final states in the nuclear equilibration process, based on the Darwin-Fowler method of statistical physics, is suggested. This method is generally valid for an arbitrary energy level scheme and includes the Pauli principle. When it is applied to the equidistant-spacing energy level scheme, the results are very close to those derived by Obložinský et al.

THE EVALUATION OF CONTEXTUAL SPEECH MATERIALS.

The energy level of contextual discourse (recorded lists of the CID Sentence Intelligibility materials) was measured by feeding the material into a speech-time analyzer. The energy levels of all 10 sentences contained in each list were integrated over 0.1 sec intervals by the analyzer, and counters displayed the amount of time that a given wave form fell below or exceeded certain arbitrary energy levels. Thus absolute energy level as well as absolute duration could be measured for each list. Intensity measurements were compared to intelligibility functions of the lists obtained by presenting each list at five signal-to-noise (S/N) ratios. Twenty normal subjects heard all 10 lists at 40 dB sensation level. Results showed no relation between absolute duration and intelligibility. Intelligibility curves for each list were evaluated in terms of the S/N ratio which yielded the 50% intelligibility point. Each list was compared in terms of its relative standing for absolute energy level and for S/N ratio at 50% intelligibility. With the exception of two lists, there was good correspondence between the rankings for absolute energy level and intelligibility. It is suggested that this measurement of speech energy levels will give a good indication of the relative intelligibility of contextual test materials.