Production Of Ultracold Ground State RbCs Polar Molecules

The study about the interaction between light and matter has been a basic way to understand the world. Nobel Prize in physics for work of laser cooling of neutral atoms, atomic Bose-Einstein condensate (BEC), optical coherence and precision spectroscopy as an important milestone, the research of ultracold atoms opened up a new world of atomic and molecular studies. Ever since laser cooling and trapping of atoms have been used to manipulate external motion and internal state of atoms, there has been a challenging goal to produce ultracold molecules with complex internal structure from ultracold atoms, especially for ultracold polar molecule. Ultracold polar molecules are of particular interest for that their dipole-dipole interactions are long-range, anisotropic, and tunable, resulting to some important applications, such as precision measurement, quantum calculation, many body problem and ultracold chemistry. In the research of ultracold polar molecules, people are most interested in the ground state molecules, which are stable and possess large electric dipole moment. The long interaction time and strong coupling of ultracold ground state molecules provide important guarantees for the achievement of the controllable and coherent quantum state. Also, the complicated rovibrational molecular structures provide favorable criteria for paralled calculation of quantum states, only a few molecular species can be used for achieving molecular direct laser cooling until now. The main methods to produce ultracold molecules are achieved by associating ultracold atoms by laser field or magnetic field. In this thesis, with the aim of formation the ultracold ground state RbCs molecule, we constitute an experimental setup for production and detection of ultracold RbCs polar molecules, construct an optimal optical transition path to produce ultracold ground state RbCs molecule through the study of the excited state high resolution photoassociation spectroscopy. The production and detection of ultracold ground state RbCs polar molecule were achieved in the experiment by short- range photoassociation and resonance-enhanced two-photon ionization method, respectively.The main innovation works are summarized below::1. A simple and reliable method is used for the temperature measurement of ultracold molecules based on the sensitive resonance-enhanced two-photon ionization detection technique. Fast temperature measurement of the ultracold molecules can be achieved, this provides a complementary method of determining the temperature of ultracold atoms and molecules.2. The target ultracold excited state RbCs polar molecules were studied in detail by using high resolution photoassociation spectroscopy, the valuable molecular constants and the precise potential energy curve were obtained, this provides a good experimental basis for the construction of the optical transition path to produce ultracold ground state RbCs molecule.3. Based on the work two, the production and detection of ultracold ground state RbCs polar molecule were achieved in the experiment by short-range photoassociation and resonance-enhanced two-photon ionization method, respectively. This work takes the applications based on ultracold molecules a step forward.4. The permanent electric dipole moment of ultracold RbCs polar molecule was precisely measured by using Stark effect, this work provides a good foundation for the control of the ultracold polar molecules by external field.