Double-slit experiment performed with molecules

For the first time, scientists have used individual molecules to act as the slits in the iconic double-slit experiment that demonstrates quantum objects behaving as both particles and waves. Researchers created an ultracold molecular beam in which helium atoms collide with deuterium molecules. They used lasers to coax each deuterium molecule into a superimposed state of two different orientations, at right angles. The helium atoms scatter off the superimposed deuterium on two different paths that interfere with each other, showing the quantum interference effect that is characteristic of the classic double-slit experiment. Because the set-up is tuneable, it could be a step towards achieving ‘quantum control’ — which would harness quantum features to manipulate chemical reactions.