Magneto-optical Trapping Of Li Atoms For Equivalence Principle Test With Dual-Species Atom Interferometers

Lithium is enjoying widespread popularity in the cold-atom trapping community thanks to the correspondingly large photon-recoil energy and lightness. The presence of these features makes lithium an attractive candidate for studies of the character of Fermi or Bose gases, s-wave regime of ion-atom collisions and large area atom interferometers. In this thesis, we develop the laser cooling and trapping of lithium atoms, the scheme of sub-Doppler cooling of lithium atoms, the design proposal of the free fall lithium atom interferometer and the analysis of major noise sources for the weak equivalence principle (WEP) test. The main work and results are listed as follows:1. Building the experimental platform of a 10-meter atom interferometer for precision gravity measurement and the equivalence principle (E-P) test, including the installing of the ultra-large setup, the vacuumizing of the ultra-large cavity, and the testing of the 10-meter atom interferometer.2. To prepare cold lithium atoms for atomic interferometry experiments, we carried out experimental research on Zeeman deceleration and magneto-optical trap (MOT) of lithium atoms. We designed and implemented a compact adjustable Zeeman slower with an inner water cooling chamber, decelerated the velocity of 7Li atom beam from 600 m/s down to 60 m/s, and loaded them into the MOT. The loading rate is 5×108/s, the total trapped atom number is 1×109, and the lowest temperature of atom cloud is 220±30 μK. We also investigate the dependence of lifetime of 7Li atoms in optical molasses on the detuning of trapping laser beams. The above results lay a foundation for further sub-Doppler cooling, optical trap based evaporative cooling, and atomic interferometry experiments.3. Designing a freefall lithium atom interferometer based on the feature of lithium, including the scheme of sub-Doppler and all-optical evaporative cooling of lithium atoms, the preparation of Raman laser pulse and the atom states for the two-photon stimulated Raman transition interference. We also analyzed the major noise sources for the WEP test briefly.4. We have demonstrated time-division-multiplexing (TDM) laser seeded optical amplification in a diode laser amplifier. With an acousto-optic modulator we combined two seeding beams of different frequencies and injected them alternately in the time domain into the tapered amplifier (TA) chip at a switching speed of 200 ns. The output high-power dual frequency components from the TA are time separated. The TDM seeded TA works safely and efficiently, which is useful for compact precision measurement instruments such as optical clocks and atom interferometers.