Hundreds of thousands of lithium atoms cooled to near absolute zero exhibit an unusual quantum effect similar to a boomerang.
|The quantum boomerang effect was observed in a vacuum of 100,000 lithium atoms.Tony Mastres/David Weld Lab at University of California, Santa Barbara
For the first time, researchers were able to demonstrate a strange phenomenon known as the quantum boomerang effect.
David Weld and his colleagues at the University of California, Santa Barbara cooled hundreds of thousands of lithium atoms to near-absolute zero inside a small vacuum-sealed box. They used lasers to align the lithium atoms in a straight line and maintain them in a quantum state that they hoped would reveal the boomerang effect.
The laser was then used to gently nudge the atoms. As a result, they went from having negative average momentum to having positive average momentum. If the same thing happened to a ball, it would roll away, but the team discovered that the atoms' average momentum quickly returned to zero due to the quantum boomerang effect.
Initially, theorists proposed that this boomerang effect could occur with electrons moving inside a crystal filled with dirt particles, but this has proven difficult to demonstrate and study. Weld and his colleagues avoided this difficulty by focusing on very cold atoms that can be precisely manipulated with lasers.
The new experiment was presented by Weld and colleagues in May at the DAMOP conference in Orlando, Florida.
He says the next step is to see if boomeranging occurs when super cold atoms interact very intensely with each other. Because the behavior of such highly coordinated atoms is poorly understood, seeing them boomerang could reveal something new about quantum physics.