The dynamic and the radiative properties of an excited three-level atom embedded in an anisotropic photonic crystal with two coherent bands are investigated.The relative position of the atom in a Wigner-Seitz cell is described with a position-dependent parameter θ(r0),which is used as the coherent parameter for the two bands.The result shows that the dynamic properties of the atomic system are not only determined by atomic transition frequencies,but also affected by the gap width and the coherence of the two bands.In addition,the spontaneous emission spectrum of the atomic transition in free space is discussed.The center and the intensity of the spectrum can be obviously manipulated via the coherent parameter.
The stereodynamic properties of the reaction C(3P)+NO(X2Π)→CN(X2Σ+)+O(3P) in different rotational states of reactant NO are studied theoretically by using the quasiclassical trajectory method on 2A'' and 2A' potential energy surfaces(PESs) at a collision energy of 0.06 eV.The vector properties in different rotational states on the two surfaces are discussed in detail.The results indicate that the rotational excitation of NO has considerable influence on the stereodynamic property of the reaction occurring on the two surfaces.At the same time,the calculated polarization-dependent differential cross sections(PDDCSs) in different initial rotational states manifest that products are strongly polarized at three scattering angles.
The elementary excitation spectrum of a two-component Bose-Einstein condensate in different hyperfine states is obtained by Green's function method. It is found to have two branches. In the long wave-length limit, the two branches of the excitation spectrum are reduced to one phonon excitation and one single-particle excitation. The single-particle one has an energy gap. When the energy gap exists, we study the Landau critical velocity and the depletion of the condensate. With the obtained Green's functions, we calculate the structure factor of a two-component condensate. It is found that the static structure factor comprises only the branch of the phonon excitation and the single-particle excitation makes no contribution to the structure factor.
