Adiabatic Condition And Quantum Control For Creating Heteronuclear Molecule

Quantum superchemistry and quantum coherent control of ultracold molecule is one of the significant areas of atom and molecule physics and optics and plays an important part in high precision measurement, quantum information storage,manipulation and extractive technology. In this paper, we focus on studying adiabatic condition for coherent atom–heteronuclear-molecule conversion, quantum squeezing effects in creating triatomic molecules from ultracold atoms, and creating atom-molecule entanglement from a two-species atomic Bose Condensate.In the first chapter, we described the phenomenon of Bose-Einstein condensation, the technology of laser cooling and neutral atom trapping, the conditions for the realization of Bose-Einstein condensation and the development of Bose-Einstein condensation at home and abroad. These provide the basis of creating ultracold molecules. Then we introduced two techniques of creating ultracold molecules, namely, optical photoassociation and magnetic Feshbach resonance, and presented the physical mechanism of creating ultracold molecules via optical photoassociation and magnetic Feshbach resonance and the current situation of creating ultracold molecules.In the second chaper, as a theoretical basis, we introduced some concepts and important experiments about quantum optics and ultracold physics, for example, HBT interference, which play a crucial role in quantum optics.In the third chaper, we have studied adiabatic conditions for coherent atom-heteronuclear-molecule conversion in two-species Bose-Einstein Condensate by using the mean-field approximation and the stimulated Raman adiabatic passage (STIRAP) technique. We have found that the formation of heteronuclear molecules was more difficult than that of homonuclear dimers and is also lower in yields, which is consistent with the results in recent experiments. For the creation of trimers, there are two different reaction paths; we obtioned two different adiabatic conditions. The yields of trimers are consistent with the results including collisions. Then we analyzed the roles of non-ideal factors, including the collisions between particles, population imbalances between initial two species atoms and quantum fluctuations. Finally, we also studied the adiabatic condition for quantum coherent abstraction reaction and made a comparation with that for linear system, atom-molecule conversion.In the fourth chaper, we have studied the quantum squeezing effects of creating homo or heteronuclear trimers by the adiabatic approximation method. Ultracold molecules exist at short time, so we considered the second order of evolution time. By preparing different squeezed atomic sample, the output molecular matter-waves have different squeezing effects and statistical distributions.In the fifth chaper, we have proposed a feasible scheme of atoms and molecules lasers, focusing on the role of the intial two species atoms imbalance on the entanglement of output atoms and molecules at short time. We made some discussion about the entanglement and their distributions in three situationes. Finally, we have analyzed the effects of decoherence on the system.In the sixth chaper, the main contents and conclusions have been summarized, and the sequentially investigative directions have been specified.