Optical tweezers perform new feats by capturing atoms

The trapping of single atoms is a bit like raising cats, which makes the University of Colorado researchers experts on feline leprechauns.

In a new study, a team led by physicist Cindy Regal showed that she could organize groups of individual atoms into large grids with unmatched efficiency by existing methods.

Isolated atoms are a potential base element for exploiting quantum physics. If researchers can capture and control these tiny pieces of matter with lasers, they can create new types of materials that behave strangely. They could also lead to quantum computers that could someday replace conventional numbering machines.

It's a big "if", say the researchers. Like these cats, neutral atoms, or atoms without charge, are not easy to tame: they spin, shatter and never remain motionless for long.

This is where Regal and his colleagues come in. In a study published recently in Physical examination X, the scientists reported that they had trapped single and neutral rubidium atoms with a 90% probability, using tiny laser beams, also known as "optical tweezers".

This new research is a step forward in mastering the slippery dynamics of atoms, said Regal, an associate professor at JILA and CU Boulder's physics department.

"The bits in a quantum computer will necessarily be small things," she said. "And every little thing has its own challenges when it comes to quarrels."

This is an approach that many researchers can take advantage of, said Mark Brown, one of the two lead authors of the new paper.

"Everyone in our field has to charge atoms," said Brown, a graduate student in physics. "So if you have a better technique for catching atoms, then a lot of people can use it."

Improve chances

Until now, scientists have used a number of techniques to charge their atoms, including using optical tweezers. In this technique, researchers first cross a series of laser beams to capture the floating atoms and cool them down.

Then it's time to bask. By carefully adjusting the energy of their lasers, scientists have discovered that they can change the behavior of their atoms, causing them to crash. As when scavenging cats, these collisions eliminate the atoms of the trap in pairs.

Finally, you only have one surviving atom left. Or at least that's what happens about half the time, Brown said.

"If you expel all pairs of atoms, you will have only one atom or atom left," he said.

His group wanted to do better than a 50% success rate. They began by using lasers of slightly different color from that chosen by atom scavengers.

Under this new illumination, the rubidium atoms no longer collided, but pushed back against each other, as if we were sticking the same poles of two magnets, Tobias said. Thiele, the other main author of the new study.

"You can now make sure that one of the atoms stays in the trap and that the other goes very far," said Thiele, a postdoctoral researcher at Regal's lab. "You end up with only one atom in the trap about nine times out of ten."

S & # 39; organize

With this level of control, researchers could not only isolate many more atoms, but also organize them more efficiently. In the new study, they said they could assemble these atoms into perfect six-by-six grids in a fraction of the time of today's tools.

The researchers, who also included graduate students Chris Kiehl and Ting-Wei Hsu, are currently working to increase this number from 36 trapped atoms to hundreds, if not thousands.

And it is at this moment that the pleasure begins. Once researchers can manage these two-dimensional or even three-dimensional networks, they can selectively tell individual atoms to connect to a neighbor via a process called quantum entanglement. Such entanglement, in which one atom is basically connected to another, is the basis of quantum computers, said Thiele.

"The good thing about this system is that you can enable and disable interactions only when you want," he said.

Which makes cats well behaved.