The Preparation Of Cold Atom Sample In Quantum Non-demolition Measurement

Quantum non-demolition measurement is one of the important researches in quantum optics, by using quantum non-demolition measurement we can generate spin squeezed states. In extremely precision measurements, such as atom interferometer in precision spectroscopy, the standard quantum limit can be surpassed by using spin squeezed states. The preparation of cold atom sample is a key work in quantum non-demolition measurement, and that is the main part of this thesis. First, the basic concepts of quantum non-demolition measurement and spin squeezed states were introduced. The development history of quantum non-demolition measurement was described. Then the physical mechanism of laser cooling and trapping of rubidium atom were discussed, including magneto-optical trap and optical dipole trap, and some parameters of the optical dipole trap were calculated by Matlab simulation. Also we present the design and construction of the experiment apparatus, a rubidium atom magneto-optical trap. By using this apparatus, we successfully realized the laser cooling and trapping of rubidium atoms, which is the first step towards cold atom sample preparation. Finally, the measurements of cold rubidium sample were done. The number and temperature of trapped atoms have been obtained.