First quantum degenerate molecules unite in chemical go-slow

Potassium–rubidium at 50 billionths above absolute zero reacts at a quarter of expected speed thanks to quantum effects

Contrary to chemistry’s usual individualism, where molecules react one by one, US researchers have forced a gas into a strangely unified condition where its components can’t be distinguished. ‘Every molecule, in some sense, knows where the others are,’ explains Luigi De Marco from JILA, a joint institute of University of Colorado, Boulder, and the US National Institute of Standards and Technology.