Cooling a Confined Bose-Einstein Condensate of a Molecule to One Millionths of Its Clouds

A strange state of matter has become more useful. Physicists have succeeded in cooling down many molecules so much that hundreds lock in step and make a quantum state. It’s possible that the systems could be used to explore exotic physics, such as creating solid materials that can flow without resistance, or a new kind of quantum computer.

The team was able to further chill the molecule without losing too much due to the repulsion. The result was a condensate of more than 1,000 molecules, cooled to 6 billionths of a degree above absolute zero. Valtolina says the hallmark of a Bose–Einstein condensate is clearly shown.

This system displays collective quantum behavior that is well controlled, and allows researchers to use it as a playground to conduct simulations of exotic kinds of magnetism and the emission of Hawking radiation from a model black hole. In the past, condensations have been used as quantum sensors and atomic clocks.

But there’s a catch. Coincidentally, the physicist at the University of Chicago mentioned that bonds are harder to control and cool than atoms.

Loosely-bound structures known as Feshbach molecules have been cajoled into condensates before. But in stable molecules, the final stage of cooling, to turn clouds of them into a condensate, has been scuppered by chemical reactions between colliding molecules. The cloud leaves too few to work with because the interactions heat the molecule and cause them to escape.

Will and his team found a way to prevent these collisions in a cloud of polar molecules, each made from one sodium and one caesium atom. The team applied two different kinds of microwave fields to the cloud, one to make the molecules rotate and another to make them oscillate. The field oriented the molecule such that they repelled each other. “This turned out to be absolutely crucial,” says Will.

Physicists will be able to predict how this strange matter will behave. Will believes that tuning the microwave fields to allow interaction between molecule will allow the system to separate into quantum droplets. By confining the condensate in two dimensions using lasers, the team also hopes to watch while the molecules arrange themselves, under a microscope, to form a kind of crystal. Will says that it has never been possible.

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