In a First, Scientists Used a Lightsaber-like Technique to Play Catch With Atoms

Subatomic baseball could speed up tomorrow’s quantum computers.

There’s nothing like a game of catch — tossing a baseball back and forth promises some old-fashioned, low-effort fun. But it’s a difficult endeavor when it involves frosty atoms and lasers.

In a new study, scientists set up a tiny game of baseball in which laser beams tossed and caught atoms. This marked the first example of laser-powered “optical traps” — which work somewhat like a Star Wars lightsaber to manipulate tiny objects — successfully throwing and receiving atoms, according to a study recently published in the journal Optica. The speedball atoms traveled 4.2 micrometers as fast as 65 centimeters per second, researchers found. In comparison, the fastest spider can crawl up to around 50 centimeters per second.

This new mechanism could eventually help power quantum computers, which have the potential to run models thousands of times quicker than today’s machines — possibly paving the way for feats like new life-saving drugs, smarter AI, and enhanced cybersecurity.

More specifically, the optical traps could quickly rearrange qubits, the quantum mechanics version of the bits found in regular computers that contain chunks of information.

“There are possibilities for moving qubits to enable more efficient and faster quantum computing,” Jaewook Ahn, a physicist at the Korea Advanced Institute of Science and Technology and co-author of the new study, tells Inverse.

What is a quantum computer?

This is a superconducting quantum processor created by D-Wave Systems Inc., one of the various approaches to run quantum computers.

D-Wave Systems, Inc./Wikimedia Commons

Scientists are still working on perfecting this type of futuristic device, which takes advantage of quantum mechanics to store data. If things pan out, these hyped-up machines could solve problems that stump even today’s supercomputers — and at exponentially higher speeds, to boot.

Nowadays, regular computers work by encoding information within content like news articles, emails, and tweets in bits, which represent the states in which electrical signals are flipped “on” or “off” with combinations of 1s and 0s. Meanwhile, a quantum machine places this info into qubits, which can be made from tiny objects that fit inside atoms — including electrons or photons.

Qubits can represent both 0 and 1 simultaneously, a mind-bending quantum property called “superposition.” This means that one of these devices can essentially do the work of four regular computers. And as scientists add more qubits to a computer, the processing abilities grow exponentially.

Potential designs for quantum computers include trapping ions with electromagnetic fields, as well as harnessing powerful superconducting electric circuits (which the company IBM is currently working on).

Another category, called neutral atom computing, relies on super-focused laser beams that suspend atoms and manipulate them to function as qubits.

In practice, qubits are finicky — they typically need to be arranged into evenly spaced arrays to properly process data, and gaps often form when scientists try to carefully load atoms into a device. But it’s hard to precisely shift around individual atoms to fill these gaps.

“Arrays of neutral atoms trapped in focused laser beams are one of the leading quantum computing platforms,” Brian Leeds DeMarco, a physicist at the University of Illinois Urbana-Champaign, tells Inverse. “A challenge for this architecture is efficiently creating a defect-free array where no atoms are missing.”

An ideal technique could approach every defect individually, instead of having to move around all the atoms in an array simultaneously. The latter “is currently a time-consuming operation,” Robert Niffenegger, a physicist at the University of Massachusetts Amherst, tells Inverse.

Laser baseball to the rescue

Research team members Hansub Hwang (left) and Andrew Byun (right) are pictured with the optical setup used to create free-flying atoms.

Jaewook Ahn, Korea Advanced Institute of Science and Technology

To approach this problem, Ahn’s team realized they could use optical traps to throw and catch specific atoms.

They started off by chilling atoms made of a metal called rubidium to nearly absolute zero and created optical traps with an 800-nanometer laser. To “throw” an atom, they held the atom in place while accelerating the trap and turned it off, launching the atom like a catapult. Then, another laser trap is turned on to catch the atom and decelerates to halt the atom in its tracks.

The scientists reported that their method worked 94 percent of the time in the recent study. But “with a lower atom temperature and more stable laser operations, this technique will be able to achieve near 100 percent” accuracy, Ahn says.

Ahn and his colleagues aren’t the first researchers to approach this problem with optical traps. Past studies have tried to guide atoms with lasers between positions — but this new method differs because it lets the atoms soar on their own, which may prove quicker and more effective.

Subatomic skepticism

While experts agree that this breakthrough could potentially ramp up quantum computing, it may come with downsides. Niffenegger points out that this new method may not work as well as similar techniques applied to ions: In trapped ion designs for quantum computers, electromagnetic fields can shuffle around ions at faster speeds and longer distances to resolve defects, he says, as demonstrated in a study published last month.

DeMarco is also skeptical. “I am not sure that this technique will be adopted by others in the field or by companies working on neutral atom quantum computing,” he says. “The success probability of throwing and catching atoms is relatively low compared with standard techniques that involve dynamic rearrangement.”

Plus, compared to other approaches, this new technique introduces a lot of extra technical complexity, DeMarco adds.

But Ahn acknowledges that this work is in the early stages and isn’t necessarily going to make its way into computers anytime soon.

“There are possibilities for moving qubits to enable more efficient and faster quantum computing because they can be dynamically rearranged during the quantum computing,” Ahn says. “However, at this moment, this is too much a claim, so we remain that our method … could be more efficient and faster for qubit preparation (not directly for quantum computing).”

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