One-dimensional far-detuned optical lattice realized with a multimode 1064 nm laser

Abstract

For a quantum memory to be useful as a quantum repeater, a long coherence time is a crucial requirement. In recent years, the most commonly explored medium for quantum storage has been atomic gases. We report an experiment to realize a quantum memory based on an Rb atomic ensemble in a one-dimensional far-detuned optical lattice. A multimode 30 W continuous wave fiber laser was used to construct a travelling wave lattice with a period of 25 m. The Rb atoms were loaded into a magneto-optical-trap, which was then adjusted to optimize the polarization gradient cooling. To trap the cooled atoms, we turned on a laser which has a wavelength of 1064 nm and therefore is red-detuned from the resonance frequencies of D1 and D2 transitions of 87Rb atoms. By taking the short-distance time-of-flight image the temperature of the atoms was found to be about 20 K. This system will provide a foundation for future quantum information storage studies.