New type of light interaction with atoms allows for manipulating cloud shape

October 24, 2017 by Bob Yirka, Phys.org report
New type of light interaction with atoms allows for manipulating cloud shape
Credit: Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.163201

A team of researchers at the Weizmann Institute of Science in Israel has found a new way to manipulate atoms using light. In their paper published in Physical Review Letters, the team describes the new technique and possible uses for it.

Up until now, scientists have used two main techniques to manipulate with . The first involves firing a at a single atom to change its momentum. The other has been to cause an atom to "feel" an electric field force associated with a beam of light. Now, researchers have developed a third technique—one that involves firing a laser at an atom cloud.

The experiments involved creating a spherical cloud consisting of nothing but millions of cold rubidium-87 atoms. The researchers then fired a pulse of infrared light at the cloud (the frequency was described as "far detuned" from rubidium-87 transitions) and found the cloud responded by behaving similarly to a lens, deflecting the light and causing the cloud to become longer and thinner—the light beam essentially squished the sphere into a new shape. The researchers note that the parameters of the beam they fired at the cloud had been idealized to reduce the force between the light's electric field and the individual rubidium atoms.

The researchers suggest the change in cloud shape resulted from the collective effect of the laser acting on all of the atoms in the cloud—conservation of momentum caused the atoms to respond to a force pushing against them in a direction opposite the deflection. The team has invented a term to describe the overall effect: electrostriction. They note that they ran their experiments on booth Bose-Einstein condensates and at higher temperatures.

Because it is a global optical , the researchers note, it could be easily modified to allow for easy tuning of interactions with lasers—an improvement over the current cumbersome method. They suggest their technique might prove useful in future cold atom experiments because it allows inducing interparticle interactions that can be easily turned.

Explore further: Proposed method to cause an atom to emit the same light as another atom

More information: Noam Matzliah et al. Observation of Optomechanical Strain in a Cold Atomic Cloud, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.163201

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big_hairy_jimbo
not rated yet Oct 25, 2017
So what was the force if not the electric field? How was the momentum transferred?

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