We prepare heralded single photons from a photon pair source based on non-degenerate four-wave mixing in a cold atomic ensemble via a cascade decay scheme. Their statistics shows strong antibunching with g(2)(0) < 0.03, indicating a near single photo
n character. In an optical homodyne experiment, we directly measure the temporal envelope of these photons and find, depending on the heralding scheme, an exponentially decaying or rising profile. The rising envelope will be useful for efficient interaction between single photons and microscopic systems like single atoms and molecules. At the same time, their observation illustrates the breakdown of a realistic interpretation of the heralding process in terms of defining an initial condition of a physical system.
We consider the near-resonant interaction between a single atom and a focused light mode, where a single atom localized at the focus of a lens can scatter a significant fraction of light. Complementary to previous experiments on extinction and phase
shift effects of a single atom, we report here on the measurement of coherently backscattered light. The strength of the observed effect suggests combining strong focusing with the well-established methods of cavity QED. We consider theoretically a nearly concentric cavity, which should allow for a strongly focused optical mode. Simple estimates show that in a such case one can expect a significant single photon Rabi frequency. This opens new perspectives and a possibility to scale up the system consisting of many atom+cavity nodes for quantum networking due to a significant technical simplification of the atom--light interfaces.
We report on a direct measurement of a phase shift on a weak coherent beam by a single Rb-87 atom in a Mach-Zehnder interferometer. A maximum phase shift of about 1 degree is observed experimentally.
We construct new charged static solutions of the Einstein-Maxwell field equations in five dimensions via a solution generation technique utilizing the symmetries of the reduced Lagrangian. By applying our method on the multi-Reissner-Nordstrom soluti
on in four dimensions, we generate the multi-Reissner-Nordstrom solution in five dimensions. We focus on the five-dimensional solution describing a pair of charged black objects with general masses and electric charges. This solution includes the double Reissner-Nordstrom solution as well as the charged version of the five-dimensional static black Saturn. However, all the black Saturn configurations that we could find present either a conical singularity or a naked singularity. We also obtain a non-extremal configuration of charged black strings that reduces in the extremal limit to a Majumdar-Papapetrou like solution in five dimensions.
