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%.
The physicists say their demonstration could be used to develop faster quantum computers capable of switching out information in arrays of atoms at rapid speed.
"These types of flying atoms could enable a new type of dynamic quantum computing by allowing the relative locations of qubits — the quantum equivalent to binary bits — to be more freely changed," said Ahn. "It could also be used to create collisions between individual atoms, opening a new field of atom-by-atom chemistry."
