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We derive a set of optical Bloch equations (OBEs) directly from the minimal-coupling Hamiltonian density of the bound-state quantum electrodynamics (bound-state QED). Such optical Bloch equations are beyond the former widely-used ones due to that there is no electric dipole approximation (EDA) on the minimal-coupling Hamiltonian density of the bound-state QED. Then our optical Bloch equations can describe a two-level atom interacting with a monochromatic light of arbitrary wavelength, which are suitable to study the spectroscopy and the Rabi oscillations of two-level atoms in X-ray laser beams since that the wavelength of X-ray is close to an atom to make the electric dipole approximation (EDA) invalid., 6 pages, 3 figures

We use the S-matrix formalism of bound-state QED to study the photon-atom scattering. We find that the internal lines in Feynman diagrams which describing the propagation of off-shell bound electrons provide the off-shell amplitudes of photons' propagation in atoms phenomenally. Our work set up the connection between the property of Feynman propagators in bound-state QED and the superluminal but casual propagating behavior of light in atomic media. We also studied the relation between the bound-state QED and the widely used light-atom interacting model in quantum optics, and give the experimental condition where only the bound-state QED is valid., 8 pages, 4 figures

We present the origin of the Abraham-Minkowski controversy of light-matter wave interacting system, which is a special case of the centaury-old Abraham-Minkowski controversy. We solve the controversy of laser-atom interacting case and find that for systems with perfect atomic spatial coherence, the systems prefer to show Minkowski momentum and canonical momentum for the atoms and light, respectively; while for the systems where the atoms are spatially incoherent, the momenta of light and atoms would choose the Abraham and kinetic forms. The provement of our solution can be realized with current techniques, using three-dimensional optical lattices and electromagnetically-induced absorption (EIA) to distinguish the kinetic and canonical recoil momentum of ultra-cold atoms., Comment: 4 pages, 3 figures

In this paper we report an experiment on the observation of the recoil-induced resonances (RIR) and electromagnetically induced absorption (EIA) of cold Rb87 atoms in diffuse light. The pump light of the RIR and the EIA comes from the diffuse light in an integrating sphere, which also serves the cooling light. The probe light beam is a weak laser split from the cooling laser in order to keep the cooling and probe lasers correlated. We measured the RIR and the EIA signal varying with the detuning of the diffuse laser light, and also measured the temperature of the cold atoms at the different detunings. The mechanism of RIR and EIA in the configuration with diffuse-light pumping and laser probing is discussed, and the difference of nonlinear spectra of cold atoms between in diffuse-light cooling system and in optical molasses as well as in a magneto-optical trap (MOT) are studied., 9 pages, 6 figures

In this paper we describe an experiment of efficient cooling of $^{87}$Rb atoms in two-frequency diffuse laser lights. Compared with single frequency diffuse light, two-frequency diffuse lights have wider velocity capture range and thus can cool more atoms. In our experiment, the maximum number of cooled atoms can reach up to $3.9\times10^9$. Such a result is quite useful in building a compact cold atom clock., Comment: 4pages, 4figures

This paper reports an experiment on laser cooling of 87Rb atoms in pulsed diffuse light, which is the key step towards a compact cold atom clock. It deduces an empirical formula to simulate the pulse cooling process based on the loading of cold atoms in cooling time and the loss in the dead time, which is in agreement with the experimental data. The formula gives a reference to select the parameters for the cold atom clock.

We present an experimental measurement of the lifetime of the cold 87Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the integrating sphere. Our result shows that the lifetime is primarily determined by the free fall of the cold 87Rb atoms, and its half-life can reach 40 ms, which is suitable for many experiments, especially for a cold atom clock.

In this paper, the theory of atomic cooling in an integrating sphere is studied. During designing an integrating sphere system, the effects of the parameters of the sphere on the cooling, including the reflectivity of the material, the shape of the sphere and holes in the sphere have been considered carefully. The experiment of 87Rb atomic cooling in an integrating sphere was performed. The experimental results show that the atoms in the integrating sphere are cooled down evidently. And the relation between the detuning of the cooling laser and the absorption signal of cold atoms was measured.