Controlled generation of single photons in a cavity QED system - Christian Nölleke

Quantum Information Processing (QIP) in quantum networks relies on the coherent exchange of information between light and matter. Neutral atoms trapped in high-finesse optical cavities are ideal candidates for such light-matter interfaces and can also offer a platform which would enable QIP with linear optics. We generate single-photon streams via a vacuum-stimulated Raman adiabatic passage, using a single Rubidium atom trapped in a cavity. In comparison to other sources, the coherence of the production process allows us to have full control over the temporal shape, frequency, polarization and phase of the photons. A fundamental prerequisite for the experimental realization of applications in QIP is a high efficient photon production process. A careful tuning of all experimental parameters has now allowed us to boost the photon generation efficiency to 60%, much higher than in previous experiments. Moreover, the duty cycle of the experimental sequence is now close to unity, owing to atom trapping times of more than one minute on average. With such an optimized setup, it is now possible to run the system in a quasi-permanent operation. We report on the current status of the experiment and present prospects for highly efficient single-photon servers as quantum memories.