Feb. 08, 2006 (Wednesday)

Efficient Coupling of Atoms and Light

James Thompson
Department of Physics, MIT

The long coherence times of trapped atoms makes them ideal storage media for quantum information. In contrast photons can rapidly transport quantum information, but are poorly suited for storage. We will discuss progress using laser cooled atomic ensembles in low finesse optical cavities to strengthen the matter-light interaction with the ultimate goal of efficient exchange of quantum information between the two media. In this work, collective spin-gratings within the ensemble are used to store an excitation and convert it "on demand" into a photon in a mode amendable to fiber coupling and transport. We observe >50% peak conversion efficiencies of the stored excitation, as well as large sub-poissonian correlations with the initial herald photon that signals the spontaneous creation of a spin-grating. The quantum memory aspect makes this system useful for applications such as quantum repeaters and triggerable single photon sources. Operating at zero delay time, the system acts as a source of photon pairs with spectral brightness three orders of magnitude greater than achieved with nonlinear crystals. Lastly, the near indistinguishability of the generated photon pairs is demonstrated via a simple two-photon interference experiment.

Time: 3:00 pm
Location: Lecture Room 5

The reception will be at 2:30 pm in room N201