Scientists use optical tweezers to play world's smallest game of catch with individual atoms

An artist's impression of the atom being launched between the two pairs of optical tweezers.

(Image credit: Jaewook Ahn, Korea Advanced Institute of Science and Technology)

Scientists using tiny optical tweezers have played the world's smallest game of catch — throwing and catching individual atoms using light.

The feat, achieved with highly-focused laser beams that held atoms in place before launching them, is the first time that atoms have been thrown from one pair of optical tweezers to another. The researchers describe the achievement in a paper published Mar. 9 in the journal Optica.

"The freely flying atoms move from one place to the other without being held by or interacting with the optical trap," co-author Jaewook Ahn, a physicist at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, said in a statement. "In other words, the atom is thrown and caught between the two optical traps much like the ball travels between the pitcher and a catcher in a baseball game."

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To send their particles flying, the physicists cooled rubidium atoms to near absolute zero temperatures before placing them inside one of two optical tweezers, which secured the atoms in place with a laser beam. Then, by accelerating the tweezers holding the atom before abruptly switching them off, the researchers launched the rubidium atom over a distance of 4.2 micrometers (less than a quarter of the width of a human hair) at speeds up to 25 inches (65 centimeters) per second. An adjacent pair of optical tweezers then caught the atoms after each throw, stopping them completely.

The researchers fleshed their method out further with a series of proof-of-principle experiments. They showed that the atoms could be thrown unimpeded through stationary optical tweezers holding other atoms, and could even be thrown precisely to form perfect arrays of atoms inside the receiving tweezer. Free-flying atoms hit their target 94% of the time; the researchers are now working to bring that up to 100%.

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Ben Turner is a U.K. based writer and editor at Live Science. He covers physics and astronomy, tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.