arXiv subjects
Publications and source records attributed to Bai-Jun Zhang.
It is well known that Schrödinger's equation is only suitable for the particle in conservative force field. In atomic and molecular field, a particle can suffer the action of non-conservative force. In this paper, a new quantum wave equation is proposed, which can describe the particle in non-conservative force field. We think the new quantum wave equation can be used in many fields.
In this paper, we study the laser cooling mechanisms with a new quantum theory approach by applying a new Schrodinger equation, which can describe a particle in conservative and non-conservative force field. With the new theory, we prove the atom in laser field can be cooled, and give the atom cooling temperature, which is accordance with experiment result. Otherwise, we give new prediction that the atom cooling temperature is directly proportional to the atom vibration frequency. By calculation, we find they are: $T=0.4334ω$.
In the paper, we present a new kind of function photonic crystals, which refractive index is a function of space position. Unlike conventional PCs, which structure grow from two materials, A and B, with different dielectric constants $ε_{A}$ and $ε_{B}$. By Fermat principle, we give the motion equations of light in one-dimensional, two-dimensional and three-dimensional function photonic crystals. For one-dimensional function photonic crystals, we study the dispersion relation, band gap structure and transmissivity, and compare them with conventional photonic crystals. By choosing various refractive index distribution function $n(z)$, we can obtain more width or more narrow band gap structure than conventional photonic crystals.
We know Schrödinger equation describes the dynamics of quantum systems, which don't include temperature. In this paper, we propose finite temperature Schrödinger equation, which can describe the quantum systems in an arbitrary temperature. When the temperature T=0, it become Shrödinger equation.
We propose some nonlinear Schrödinger equations by adding some higher order terms to the Lagrangian density of Schrödinger field, and obtain the Gross-Pitaevskii (GP) equation and the logarithmic form equation naturally. In addition, we prove the coefficient of nonlinear term is very small, i.e., the nonlinearity of Schrödinger equation is weak.
We provide a quantum approach description of neutron single and double-slit diffraction, with specific attention to the cold neutron diffraction ($λ\approx 20$Å) carried out by Zeilinger et al. in 1988. We find the theoretical results are good agreement with experimental data.
We have analyzed the $D\rightarrow πK, KK$ decay with the naive factorization (NF), QCD factorization (QCDF)and QCD factorization including soft-gluon exchanges (QCDF+SGE). In these decay channels, the soft-gluon effects are firstly calculated with light cone QCD sum rules. Comparing the three kind approaches, we can find the calculation results have made much more improved QCD factorization (QCDF) than the naive factorization (NF), and the calculation results have also made improved QCD factorization including soft-gluon exchanges (QCDF+SGE) than the QCD factorization (QCDF) in the color-suppressed decay channels. In addition, we find the soft-gluon effects are larger than the leading order contributions, and the calculation results are close to the experimental data for the color-suppressed decay channels. In color-allowed decay channel $D^{0}\rightarrow π^{+} K^{-}$, the soft-gluon effects are small and we should consider other power terms, such as final state interaction and annihilation effects.
At present, the theory of light diffraction only has the simple wave-optical approach. In this paper, we study light diffraction with the approach of relativistic quantum theory. We find that the slit length, slit width, slit thickness and wave-length of light have affected to the diffraction intensity and form of diffraction pattern. However, the effect of slit thickness on the diffraction pattern can not be explained by wave-optical approach, and it can be explained in quantum theory. We compare the theoretical results with single and multiple slits experiment data, and find the theoretical results are accordance with the experiment data. Otherwise, we give some theory prediction. We think all the new prediction will be tested by the light diffraction experiment.
As well known, an electron will produce radiative reaction force when the electron emits electromagnetism radiation. The electron radiative effect had not been considered in Schrödinger wave equation. In this paper, we give the nonlinear quantum wave equations for the radiative electron and some dissipative systems.
Experiments done with single photon in the early 1990's produced a surprising result: that single photon pass through a photon tunnel barrier with a group velocity faster than the vacuum speed of light. Recently, a series of experiments revealed that electromagnetic wave was able to travel at a group velocity faster than $c$. These phenomena have been observed in dispersive media. We think all particles can be divided into three kinds in nature: The first kind of particle is its velocity in the range of $0\leq v < c$, e.g. electron, atom and so on. The second kind of particle is its velocity in the range of $0\leq v < c_{m}$, e.g. photon. The third kind of particle is its velocity in the range of $c\leq v < c_{m}$ ($c_{m}$ is the maximum velocity in universe), e.g. tachyon. The first kind of particle is described by the special relativity. In this paper, we give some new kinematic and dynamic equations to describe the second and third kinds particles.
The phenomena of electron, neutron, atomic and molecular diffraction have been studied by many experiments, and these experiments are explained by some theoretical works. In this paper, we study electronic double-slit diffraction with quantum mechanical approach. We can obtain the results: (1) When the slit width $a$ is in the range of $3λ\sim 50λ$ we can obtain the obvious diffraction patterns. (2) when the ratio of $\frac{d+a}{a}=n (n=1, 2, 3,\cdot\cdot\cdot)$, order $2n, 3n, 4n,\cdot\cdot\cdot$ are missing in diffraction pattern. (3)When the ratio of $\frac{d+a}{a}\neq n (n=1, 2, 3,\cdot\cdot\cdot)$, there isn't missing order in diffraction pattern. (4) We also find a new quantum mechanics effect that the slit thickness $c$ has a large affect to the electronic diffraction patterns. We think all the predictions in our work can be tested by the electronic double-slit diffraction experiment.