Within tiny halos of light clinging to a vanishingly thin wisp of optical fiber, scientist Jongmin Lee guides atoms like marbles through a narrow pipe. Rock the fiber and the atoms shift side by side; they just don't fall off. But don't be deceived by the seemingly delicate nature of his experiment. Lee is exploring how to measure motion precisely in rough-and-tumble environments.

Tiny manufacturing imperfections in optical components normally go unnoticed. Yet they can alter light in surprisingly significant ways. An international research team led by TU Darmstadt has shown that such imperfections can affect not only polarization—the direction in which light oscillates—but also the spatial shape of a light beam.