'Tornadoes' are transferred from light to sodium atoms

November 9, 2006
'Tornadoes' are transferred from light to sodium atoms
Quantum weirdness: Pictures of a BEC 'cloud' of sodium atoms in the NIST experiment to transfer rotational energy to a quantum system show the cloud (a) rotating in a donut-shaped vortex, and interfering with itself as the cloud (b) simultaneously rotates in opposite directions, and (c) simultaneously rotates and stands still. Rotational energy is transferred in quantized amounts. False-color images show (d) one and (e) two units of rotational motion. Credit: NIST

For the first time, tornado-like rotational motions have been transferred from light to atoms in a controlled way at the National Institute of Standards and Technology. The new quantum physics technique can be used to manipulate Bose-Einstein condensates (BECs), a state of matter of worldwide research interest, and possibly used in quantum information systems, an emerging computing and communications technology of potentially great power.

As reported in the Oct. 27 issue of Physical Review Letters, the research team transferred orbital angular momentum--essentially the same motion as air molecules in a tornado or a planet revolving around a star--from laser light to sodium atoms.

The NIST experiment completes the scientific toolkit for complete control of the state of an atom, which now includes the internal, translational, and rotational behavior. The rotational motion of light previously has been used to rotate particles, but this new work marks the first time the motion has been transferred to atoms in discrete, measurable units, or quanta. Other researchers, as well as the NIST group, previously have transferred linear momentum and spin angular momentum (an internal magnetic state) from light to atoms.

The experiments were performed with more than a million sodium atoms confined in a magnetic trap. The atoms were chilled to near absolute zero and in identical quantum states, the condition known as a Bose-Einstein condensate in which they behave like a single "super-atom" with a jelly-like consistency. The BEC was illuminated from opposite sides by two laser beams, one of them with a rotating doughnut shape.

Each atom absorbed one photon (the fundamental particle of light) from the doughnut laser beam and emitted one photon in the path of the other laser beam, picking up the difference in orbital angular momentum between the two photons. The interaction of the two opposing lasers created a corkscrew-like interference pattern, inducing the BEC to rotate--picture a rotating doughnut, or a vortex similar to a hurricane.

The researchers demonstrated control over the process by inducing the cloud of atoms to simultaneously rotate and stand still, or to rotate simultaneously in opposite directions with varying amounts of momentum--a mind-bending peculiarity of quantum physics known as superposition.

Citation: M.F. Andersen, C. Ryu, P. Cladé, V. Natarajan, A. Vaziri, K. Helmerson, and W.D. Phillips. 2006. Quantized rotation of atoms from photons with orbital angular momentum. Physical Review Letters. Oct. 27.

Source: NIST

Explore further: 2D materials researchers aim 'beyond graphene'

Related Stories

Recommended for you

The sound of music, according to physicists

July 30, 2015

Joshua Bodon is sick of hearing "Somewhere Over the Rainbow." More specifically, he's sick of hearing one 25-second clip of the song repeated more than 550 times.

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

Rogue wave theory to save ships

July 29, 2015

Physicists have found an explanation for rogue waves in the ocean and hope their theory will lead to devices to warn ships and save lives.

Scientists unlock secrets of stars through aluminium

July 29, 2015

Physicists at the University of York have revealed a new understanding of nucleosynthesis in stars, providing insight into the role massive stars play in the evolution of the Milky Way and the origins of the Solar System.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.