Atoms and Light

Wang Ju-xia

The evolution of quantum information of light field fidelity in the percedure interaction between two atoms and light field under considering atom-atom coupling and intensity-dependent coupling are investigated by mean of full quantum theory and numerical computation method.The results show that the light field fidelity relates closely with intensity of initial light field,coefficient of field-atom coupling,and coefficient of atom-atom coupling.The influence of these factors leads to fidelity oscillation.It is advantageous of improving the light field fidelity if controlling and making intensity of light weak and atom-atom coupling strong.The more stronger initial light intensity or atom-field coupling,the faster the frequency of light field fidelity and the more obvious varying regularity.The fidelity present also collapse-revert when initial light intensity or atom-atom coupling is strong.The light field could keep steady state during strongly coupling between atom and light field.

Amit Goswami

Andrew S. Milman

Cheng Qiu, Shuying Chen, L. Q. Chen +4 more

Coherent wave splitting is crucial in interferometers. Normally, the waves after this splitting are of the same type. But recent progress in interaction between atom and light has led to the coherent conversion of photon to atomic excitation. This makes it possible to split an incoming light wave into a coherent superposition state of atom and light and paves the way for an interferometer made of different types of waves. Here we report on a Rabi-like coherent-superposition oscillation observed between atom and light and a coherent mixing of light wave with excited atomic spin wave in a Raman process. We construct a new kind of hybrid interferometer based on the atom-light coherent superposition state. Interference fringes are observed in both optical output intensity and atomic output in terms of the atomic spin wave strength when we scan either or both of the optical and atomic phases. Such a hybrid interferometer can be used to interrogate atomic states by optical detection and will find its applications in precision measurement and quantum control of atoms and light.

Antony Hewish

Bing Yuan

For the interaction of two entangled atoms with the two-mode squeezed light field,the entanglements between the atom with the light field and that between the two-modes of the light field are studied.Setting that one atom is outside the cavity and the other atom enters the cavity to interact with the light field,generally the entanglement changes periodically and the period is not affected by the rotation angle of the outside atom and the phase difference in the atomic entangled state.But,if the squeezing parameter of the light field and the rotation angle of the atom outside the cavity satisfy a certain relation,atom and the light field will be disentangled forever.