Two rubidium atoms were used to create the molecule which survived for 18 microseconds.

Related experiments have been done in a vapor of rubidium atoms, Dr. Leonhardt said.

They want to be able to tell if a rubidium atom is in a particular state.

"A condensate of rubidium atoms will certainly not be silvery," he said.

If the rubidium atom is in one state, the light has the right wavelength to excite it to a higher energy state.

This condensation only happens at very low temperatures: around 170 nanokelvins for rubidium atoms.

The experiment was performed using ultracold rubidium atoms.

Most likely they formed molecules consisting of two bonded rubidium atoms.

Their approach involved sending individual rubidium atoms, each in a superposition of two states, through a microwave-filled cavity.

In this compound, rubidium atoms were the ones close to the absorption edge.