|
'Tornadoes' are transferred from light to sodium atoms
November 10, 2006For 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 (NIST). 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.
National Institute of Standards and Technology (NIST)
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.
National Institute of Standards and Technology (NIST)
NIST announces first observation of 'persistent flow' in a gas
Using laser light to stir an ultracold gas of atoms, researchers at the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (NIST/University of Maryland) have demonstrated the first "persistent" current in an ultracold atomic gas -a frictionless flow of particles.
Scientists 'Weigh' Tiny Galaxy Halfway Across Universe
A tiny galaxy, nearly halfway across the universe, the smallest in size and mass known to exist at that distance, has been identified by an international team of scientists led by two from the University of California, Santa Barbara.
Sodium loses its luster: A liquid metal that's not really metallic
When melting sodium at high pressures, the material goes through a transition in which its electrical conductivity drops threefold.
In tiny supercooled clouds, physicists exchange light and matter
Physicists have for the first time stopped and extinguished a light pulse in one part of space and then revived it in a completely separate location.
Binary asteroid in Jupiter's orbit may be icy comets from solar system's infancy
Astronomers at the University of California, Berkeley, working with colleagues in France and at the Keck Telescope in Hawaii, have calculated the density of a known binary asteroid system that shares Jupiter's orbit, and concluded that Patroclus and its companion probably are composed mostly of water ice covered by a patina of dirt.
More Sodium Atoms News Articles
| © 2008 BrightSurf.com |