Abstract : In the three last decades, laser cooling techniques made a huge progress, enabling the realization of high precision devices, such as atomic clocks and gravimeters, based on a perfect control of the interaction between light and matter. Single ions or atoms, in a well-controlled motional state, appear as the ultimate carrier of information for a quantum computer. The road to the quantum computer makes necessary the integration and miniaturisation of the technology which allows to manipulate the atoms with such a high precision. The atomchips represent a big step towards this goal, providing a dramatic reduction to the requirements in terms of volume and cost of laser cooling experiments. Current developments of atomchips technology are largely focused on the realization of integrated devices which extend capabilities in terms of atomic manipulation.
In this thesis, we demonstrate the first detector for trapped single atoms, integrated to an atomchip. The detection device is a high finesse Fabry-Perot optical cavity, in the strong coupling regime of cavity QED. The cavity allows to perform a quantum-non-destructive measurement of the atomic hyperfine number, and perturbs the atomic motional state much less than a free space optical detector. We use this measurement device also to prepare a single atom in a well-defined internal state.
Relying on the preparation and measurement of the atomic state with the cavity, we carry out the first Quantum Zeno Effect experiment performed with single, neutral atoms. Under continuous measurement, we show that Rabi oscillations between hyperfine ground states are slowed down and eventually frozen. This experiment clearly proves that the decoherence induced by a cavity-based detector is totally dominated by the leakage of cavity photons, and not the atomic spontaneous emission.