An ambitious experiment to make a glass sphere exist in two places at once could provide the most sensitive test of quantum theory yet. The experiment will place a sphere containing millions of atoms – making it larger than many viruses – into a superposition of states in different places, say researchers in Europe.
Physicists have questioned whether large objects can follow quantum laws ever since Erwin Schrödinger's thought-experiment suggested a cat could exist in a superposition of being both alive and dead.
The idea is to zap a glass sphere 40 nanometres in diameter with a laser while it is inside a small cavity. This should force the sphere to bounce from one side of the cavity to the other. But since the light is quantum in nature, so too will be the position of the sphere. This forces it into a quantum superposition.