Molecules/Matter & Energy

An atom steps in as a mirror, ladybug chemical weapons and more in this week's news

Atomic mirror
A single atom that acts like a mirror won’t do much for your personal hygiene. But it could lead to transistors for computers that use light instead of electricity to perform computations. Researchers in Austria trapped a single barium ion, cooled it with a laser and used it to replace one of the mirrors in a Fabry-Pérot interferometer — a device that filters or amplifies light by bouncing it between a pair of mirrors. When energized by light of the proper wavelength the ion became reflective, the researchers report in an upcoming Physical Review Letters.Devin Powell

A sound wave traveling from the lower right corner to the upper left creates regular peaks (red) and troughs (blue-green) in energy that carry electrons through a channel (middle) on the surface of a semiconductor. Robert McNeil

A chemical weapon of the harlequin ladybug may be key to the invasive species’ success. Harmonine, a compound exuded through the beetle’s leg joints in a process known as “reflex bleeding,” is super toxic, halting the growth of the parasite that causes malaria, several species of bacteria (including drug-resistant staph) and even human cells, scientists in Germany report September 21 in Biology Letters. Praised for its voracious appetite, Harmonia axyridis has been shipped around the world to feast on plant pests. But in a very unladylike manner, the ladybug has overstayed its welcome in many places and multiplied. Understanding harmonine’s antimicrobial powers won’t stop the ladybug, but it could lead to new drugs. —Rachel Ehrenberg

Electrons hang ten
Electrons have learned how to surf sound waves on the surfaces of semiconductors. Riding in the trough of such a wave created by a small device that vibrates the surface, a single electron can now travel farther than ever before without being disturbed by other electrons — a useful trick for quantum circuits that would enlist these particles to carry information. Reporting in the Sept. 22 Nature, one international team of researchers transported single electrons several micrometers between two quantum dots, clumps of atoms that can trap and release electrons. A separate team at the University of Cambridge, also publishing in Nature, shuttled the same electron back and forth between quantum dots more than 60 times. —Devin Powell

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