干涉现象中能量叠加的实验研究

经典的波动理论与量子理论均分别对杨氏双缝干涉实验进行了解释。由于两个解释理论一个简单直观、一个复杂抽象,但两者结果一致,使得学生在学习中容易接受波动理论而排斥量子理论。文中通过实验观测了杨氏双缝干涉光场中能量传递与叠加的实际情况,结果显示实验实际情况与波动理论解释明显不相符合,而与量子理论解释完全相符。通过实验,使学生直观地看到波动理论的局限性,并加深学生对量子力学相关理论的理解。     

Scattering theory of defects in crystals

The theory of scattering is applied here to the problem of the electronic states of impurities. The S, T and K matrices, the Lippman-Schwinger and Dyson equations are used to formulate the problem. The standard concepts, methods and results of scattering theory applied to impurities discussed include the scattering amplitude, the Fredholm determinant, dispersion relations, Regge poles, Levinson's theorem and Fadeev's equations. Physical consequences considered are the change in density of states, eigenstates and transport theory. The necessity of extending the scattering formalism to many-body theory is discussed. The relation between scattering theory and other methods of impurity theory is also mentioned.     

Macroscopic excitations in superconductors

The dynamical density functional theory (DDFT) as an alternative approach to the mode coupling theory (MCT) for supercooled liquids and glass transitions was recast in the path integral form, which can then be analyzed by the methods of equilibrium statistical mechanics. The hope is to avoid drastic approximations entering the original MCT such as factorization of the multiparticle correlation function. The renormalized perturbation theory is developed and the freezing is interpreted as a result of the life-time renormalization. The multicomponent extension of the theory is proposed, which could be treated exactly in the limit of infinite number of the components.     

Quantization in the large

A model theory is constructed that exhibits quantization on a cosmic scale. A holistic rationale for the theory is discussed. The theory incorporates a fundamental length, of cosmic size, and preserves the weak, geometrical equivalence principle. The momentum operator is an integral, nonlocal, naturally contravariant operator, in contrast to the usual quantum case. In the limit of high quantum numbers the theory reduces to classical physics, giving rise to a world which is quantized both on the microscopic and cosmic scale, each of which passes over to the usual macroscopic, continuous, classical, world in the highn limit. The theory is applied to two experimental situations, absorption lines in high-z quasars and elliptical rings around normal galaxies, with suggestive but not definitive results.     

磁控管的电荷分布

回顾了几种磁控管理论模型,对这些理论模型中得到的电荷分布进行了分析。利用计算机对X波段磁控管进行PIC模拟,监视粒子相空间分布,并与理论结果进行对比,证明布里渊理论能部分解释轮轭层的高度及其内部的电荷密度分布,但模拟结果中电子在相空间存在一定的分布,而布里渊理论采用的是单粒子运动理论,因此无法解释模拟结果中轮轭边界下降沿特性。模拟得到的轮辐内电荷分布与各种理论均有较大差异,分析发现,不同的轮轭边界下降沿特性是造成差异的主要原因。讨论了利用导向中心流体理论得到更准确的轮辐内电荷分布的可能方法。     

Nuclear Reactions in Micro/Nano-Scale Metal Particles

Low-energy nuclear reactions in micro/nano-scale metal particles are described based on the theory of Bose–Einstein condensation nuclear fusion (BECNF). The BECNF theory is based on a single basic assumption capable of explaining the observed LENR phenomena; deuterons in metals undergo Bose–Einstein condensation. The BECNF theory is also a quantitative predictive physical theory. Experimental tests of the basic assumption and theoretical predictions are proposed. Potential application to energy generation by ignition at low temperatures is described. Generalized theory of BECNF is used to carry out theoretical analyses of recently reported experimental results for hydrogen–nickel system.     

Systematic low-energy effective theory for magnons and charge carriers in an antiferromagnet

By electron or hole doping quantum antiferromagnets may turn into high-temperature superconductors. The low-energy dynamics of antiferromagnets are governed by their Nambu–Goldstone bosons—the magnons—and are described by an effective field theory analogous to chiral perturbation theory for the pions in strong interaction physics. In analogy to baryon chiral perturbation theory—the effective theory for pions and nucleons—we construct a systematic low-energy effective theory for magnons and electrons or holes in an antiferromagnet. The effective theory is universal and makes model-independent predictions for the entire class of antiferromagnetic cuprates. We present a detailed analysis of the symmetries of the Hubbard model and discuss how these symmetries manifest themselves in the effective theory. A complete set of linearly independent leading contributions to the effective action is constructed. The coupling to external electromagnetic fields is also investigated.     

Spin wave excitations in amorphous itinerant ferromagnet

The Izuyama, Kim and Kubo theory of spin waves in crystalline itinerant ferromagnets is extended to the amorphous itinerant ferromagnetic materials. The qualitative features of this theory are similar to that of the generalized Landau-Lifshitz theory discussed by Henderson and de Graaf.     

表面等离子共振效应中传统近似理论与薄膜光学理论

指出Kretschmann模型的传统表面等离子共振公式在求解金属薄膜的参量时存在近似性,采用更为严密的薄膜光学理论,通过薄膜膜系的特征矩阵,得出表面等离子体共振衰减曲线.结果表明,表面等离子体共振近似理论与薄膜光学理论得到的共振角及反射率幅度存在差别;采用等高线图,给出了共振角差随着金属介电常量的变化规律.进一步的实验表明,薄膜光学理论所得模拟结果较表面等离子体共振近似理论与实验值吻合地更好,证明薄膜光学理论应用在表面等离子体共振效应要优于常用的近似理论.最后,采用两种理论对表面等离子体共振传感器进行优化设计,结果表明,两种理论所获得的高灵敏度分布区域差异较大,必须采用薄膜光学理论提供更精确的薄膜参量,来优化设计高灵敏度表面等离子体共振传感器.     

Electron transport in rectangular quantum wells

Experimental results on low-field and high-field electron transport in rectangular quantum wells are reviewed. The related theory is presented and the experimental results are examined in the light of the theory. It is concluded that although some experimental results are available and the theory of transport has been developed, numerical agreement between theory and experiments has not yet been reached. The author felicitates Prof. D S Kothari on his eightieth birthday and dedicates this paper to him on this occasion.     

An analytical theory for diffusion of fluids in crystalline nanoporous materials

An analytical theory for diffusion of fluids in zeolites and other nanoporous materials has been developed. The theory incorporates molecular level information about the nanoporous material, which is obtainable from an energy minimization and does not require molecular dynamics computer simulations. The theory is statistical mechanical in nature and assumes a lattice composed of adsorption sites. The theory yields a self-diffusion coefficient, which is a function of (i) temperature, (ii) adsorbate density, (iii) adsorbate size, (iv) adsorbate-adsorbate energetic interaction and (v) adsorbate-pore energetic interaction. The theory is generalized and is applicable to nanoporous materials with three-dimensional porous networks (e.g. faujusite) and one-dimensional porous networks (e.g. A1P0₄-5).

The theory is self-contained and incorporates no fitting parameters. The theory does not require computational effort beyond a few seconds on a standard personal computer.     

Slow rotation in the bimetric theory of gravitation

The equations describing the moment of inertia and the dragging of inertial frames of slowly rotating neutron stars are derived according to Rosen's bimetric theory of gravitation. Numerical calculations of the properties of neutron stars according to the bimetric theory and general relativity were made using several equations of state. The general trend found is that in the bimetric theory neutron stars with a given mass induce a smaller dragging of inertial frames than in general relativity. The moment of inertia of low-mass stars also is smaller in the bimetric theory. For high-mass stars, however, the moment of inertia is found to be larger in the bimetric theory.In partial fulfillment of the requirements for the D.Sc. degree.     

Spontaneous Compactification of Extra Dimensions in Eleven-Dimensional Quantum Gravity

The reduction of the eleven-dimensional pure gravity theory to a field theory to a field theory in the four-dimensional Minkowski space-time by means of the spontaneous compactification of the extra dimensions is investigated. The contribution of the quantum fluctuations of the eleven-dimensional second rank symmetric tensor field to the curvatures of the space-time and the compactified space of the extra dimensions are calculated in the one-loop approximations. It is shown that there exist the values of the cosmological constant such that the resulting four-dimensional theory is self-consistent.     

Effects of vibrational anharmonicity on 19F nuclear resonance in SF6

A Barker-Henderson like perturbation theory for polyatomic fluids is developed. The molecular interaction forces are assumed to be described by an interaction site model potential and the reference system is a fluid of hard interaction site model molecules.

The theory is used to study the equation of state of nitrogen, the theoretical results being compared with experimental data and with those coming from other theories. The agreement between theory and experiment is as good as that shown by Barker and Henderson theory for monoatomic systems.     

Minimal gravitational coupling in the Newtonian theory and the covariant Schrödinger equation

The role of the Bargmann group (11-dimensional extended Galilei group) in nonrelativistic gravitation theory is investigated. The generalized Newtonian gravitation theory (Newton-Cartan theory) achieves the status of a gauge theory about as much as general relativity and couples minimally to a complex scalar field leading to a four-dimensionally covariant Schrödinger equation. Matter current and stress-energy tensor follow correctly from the Lagrangian. This theory on curved Newtonian space-time is also shown to be a limit of the Einstein-Klein-Gordon theory.Partially supported by the Natural Sciences and Engineering Research Council of Canada, Grant No. A8059.     

Effective theory of excitations in a Feshbach-resonant superfluid

A strongly interacting Fermi gas, such as that of cold atoms operative near a Feshbach resonance, is difficult to study by perturbative many-body theory to go beyond mean-field approximation. Here I develop an effective field theory for the resonant superfluid based on broken symmetry. The theory retains both fermionic quasiparticles and superfluid phonons, the interaction between them being derived nonperturbatively. The theory converges and can be improved order by order, in a manner governed by a low energy expansion rather than by a coupling constant. I apply the effective theory to calculate the specific heat and discuss the theory with a recent heat capacity experiment.     

Conjugate variables in quantum field theory and natural symplectic structures

Within standard quantum field theory we establish relations which operators conjugate to the energy–momentum operator of the theory would have. They thus can be understood as representing the effect of coordinate operators. The non-trivial commutation relations we derive constitute natural symplectic structures in the theory. The example which is based on the energy–momentum tensor of the theory is constructed to all orders of perturbation theory. The reference theory is massless ?⁴${?}^4$. The extension to other theories is indicated.     

Electrical conductance of rings in composites

A scaling theory for describing the electrical conductance of rings in percolating systems is proposed. The theory is formulated for a given ring geometry and composition and the conductivity is expressed in terms of universal critical exponents for the infinite percolating system. Computer simulation results are found to be in good agreement with predictions of the theory.     

Fields nonlocal in clifford space

A previously proposed field theory is quantized. The theory contains a parameter having the character of an elementary length. We fix the value of this parameter by scaling it to the weak interaction strength. It is shown that this way negative metric states are confined to a region of the order 10^?15 cm. The resulting quantum theory of interacting fields is Lorentz and gauge invariant, has a unitaryS-matrix, and is convergent.