Features of Magneto-Optical Resonances in an Elliptically Polarized Traveling Light Wave

The parameters of nonlinear absorption magneto-optical resonances in the Hanle configuration have been studied as functions of the ellipticity of a traveling light wave. It has been found that these parameters (amplitude, width, and amplitude-to-width ratio) depend strongly on the polarization of the light wave. In particular, the resonance amplitude can increase by more than an order of magnitude when the polarization changes from linear to optimal elliptic. It has been shown that this effect is associated with the Doppler frequency shift for atoms in a gas. The theoretical results have been corroborated in experiments in Rb vapor.Comment: 5 page

A quantum memory with telecom-wavelength conversion

In a fibre-based quantum information network, telecom-wavelength transmission between quantum memory elements is required to minimize absorption. Owing to the paucity of suitable ground-state atomic transitions, a quantum memory interfaced with telecom light has not been previously realized. We report its demonstration by converting to telecom wavelength near-infrared light emitted on a ground-state transition. The conversion is achieved with a diamond configuration of atomic transitions, in an optically thick gas of cold rubidium. The quantum memory is also realized with cold rubidium, but confined in an optical lattice to suppress motional dephasing on a submillisecond timescale. We observe quantum memory lifetimes in excess of 0.1?s by laser compensation of the lattice light shifts that limited the previous generation of atomic memory to 7?ms. By measuring quantum correlations of light fields before and after telecom down-conversion, transmission and up-conversion, we demonstrate a basic memory element for a scalable, long-distance quantum networ

Long-lived quantum memory

Quantum memories for the storage and retrieval of quantum information are extremely sensitive to environmental influences, which limits their storage times. The ground states of atoms and ions are potential candidates for quantum memories, but although coherence times of the order of a few seconds for atoms and hundreds of seconds for ions have been demonstrated, long-lived storage and retrieval of single quantum excitations remains an outstanding challenge. Here, we report a quantum memory using the magnetically insensitive clock transition in atomic rubidium confined in a one-dimensional optical lattice. We observe quantum memory lifetimes exceeding 6 ms, more than two orders of magnitude longer than previously reported. This advance is an important step towards the realization of long-distance quantum networks and the controlled production of complex entangled states of matter and ligh