| Cavity quantum electrodynamics (Cavity QED) is to study the interaction between light confined in a reflective cavity and particles. The system provides the possibilities of investigating the quantum dynamics evolution of the the atom-photon interactions on single quanta level. The strong coupling of single atom and cavity mode can be used not only to sensitively detect a single atom in real time, but also to provide an important way for the preparation of quantum states and demonstrating quantum gates and quantum information. The primary technical challenge on the road toward this scientific goal is to trap and localize single atoms within a cavity in strong coupling regime.The thesis focuses on the measurement and control of single atoms in a strong coupling cavity QED system. The main results of this thesis are as follows:1 Single atom trapping in the cavity mode is realized. The whole cavity QED system in the lab includes vacuum chamber, high-finesse optical microcavity, frequency chain system, dipole trapping scheme, detection system and computer program control system. Base on the FPGA program, the real time feedback program is built, which make it possible to control the position of single atom in the cavity mode.2 The strong coupling between single neutral atoms and the different high order Hermite-Gaussian transverse modes such as TEMm0 (m=0,1,2,3) in a high-finesse optical micro-cavity have been observed and the higher precision of position and velocity of the individual atoms is also obtained. As the mode order increases, the precision of atomic position and velocity is also improved. The best spatial resolutions of atomic position 1.95 μm/10μs in vertical direction (axis-x) and 0.26 μm for off-axis direction (axis-y) are obtained when an atom freely falls and strongly coupled to TEM30 mode. Meanwhile the precision of atomic velocity can reach to 3mm/s3 A microcavity as an atom sensor is used to investigate the statistical characteristics of cold atoms in the initial MOT. By recording the accurate arrival time of a single atom at the cavity, the temperature of the cold atoms in MOT is determined。Using this method, the temperature of the cold atoms in MOT is measured and the minimum temperature is about 9 μK. The profile of the transmission spectrum can be retrieved eventually by superposing all the falling events and combine with the Monte Carlo simulation data and the temperature information of cold atom in the MOT can be obtained. This approach sheds new light on determining temperature of cold atoms in a confined space. We study the full counting statistics of the beam taken from the transmission spectrum of the cavity. The bunching effect for a thermal atom beam is observed.4 Double FORT in both directions of vertical and along the axis of cavity have been built. A single atom is trapped in cavity mode by means of an intracavity far-off-resonance trap (FORT) with the magic wavelength around 935nm for cesium. By this "magic" wavelength FORT, we achieve state-insensitivesingle-atom trapping and cooling in a microcavity. The average dwell time is increased up to 7 ms by introducing cavity cooling with appropriate detuning.5 The intensity noise of laser is suppressed by a photoelectric negative feedback. We theoretically analyze the optoelectronic feedback loop and then by using an optoelectronic negative feedback loop the intensity noise of laser can be suppressed between 0 and 140 kHz and the maximum intensity noise reduction of 10dB is achieved... |
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