London, Jan 8 : A team of scientists has observed a quantum effect that causes objects to repel one another, which could be used to lubricate future nanomachines.

According to a report in New Scientist, the team detected the weak repulsive force when they brought together a thin sheet of silica and a small gold-plated bead, about half the diameter of a human hair.

The force is an example of the Casimir effect, generated by all-pervasive quantum fluctuations.

The simplest way to imagine the Casimir force in action is to place two parallel metal plates in a vacuum. Thanks to the odd quantum phenomenon, these become attracted to one another.

It happens because even a vacuum is actually fizzing with a quantum field of particles, constantly popping in and out of existence. They can even fleetingly interact with and push on the plates.

However, the small space between the two plates restricts the kind of particles that can appear, so the pressure from behind the plates overwhelms that from between them.

The result is an attractive force that gums up nanoscale machines.

Harvard physicist Federico Capasso, a member of the group who measured the effect, said that that the Casimir force needn't be an enemy.

"Micromechanics at some point will have to contend with these forces - or make use of them," he said.

In 1961, Russian theorists calculated that in certain circumstances, the Casimir effect could cause objects to repel one another - a scenario Capasso's team have finally created experimentally.

The team achieved this by adding a fluid, bromobenzene, to the setup.

The Casimir attraction between the liquid and the silica plate is stronger than that between the gold bead and the silica, so the fluid forces its way around the bead, pushing it away from the plate.

The effect is akin to the buoyancy experienced in the macro world, where objects less dense than water are held up by the liquid around them. But, in this case, the bromobenzene is less dense than the solid bead.

"You could call it quantum buoyancy," Capasso told New Scientist.

The force he measured was feeble - amounting to just a few tens of piconewtons - but that is still enough to buoy up nanoscale objects.

"Harnessing the repulsive Casimir force could provide a kind of lubrication to solve the problem of nanomachines becoming gummed up by the better-known attractive version," said Capasso. (ANI)