Cross-Dressing Rubidium May Reveal Clues for Exotic Computing

Feb 25, 2009

(PhysOrg.com) -- Neutral atoms--having no net electric charge--usually don't act very dramatically around a magnetic field. But by “dressing them up” with light, researchers at the Joint Quantum Institute, a collaborative venture of the National Institute of Standards and Technology and the University of Maryland at College Park, have caused ultracold rubidium atoms to undergo a startling transformation.

They force neutral atoms to act like pointlike charged particles that can undergo merry-go-round-like “cyclotron” motions just as electrons do when subjected to a suitable magnetic field. This extreme makeover for ultracold atoms promises to give physicists clues on how to achieve an exotic form of computation that would rely upon special “fractionally charged” particles dancing around on a surface.

Just as good theatrical plays provide teachable insights about complex human situations, ultracold atomic gases are ideal proxies for studying complex phenomena in physics. Since it is relatively easy to manipulate the energy levels of ultracold atoms in gases and to control the interactions between them, scientists can learn important clues about physical phenomena that occur in more complicated and less controllable liquid or solid systems.

Among such complex phenomena are the quantum Hall and fractional quantum Hall effects, the subjects of the 1985 and 1998 Nobel Prizes in physics. In the latter effect, low-temperature electrons, confined to a plane and placed in high magnetic fields, can act as if they form “quasiparticles” carrying a fraction of an electric charge as well as several bundles of magnetism known as “magnetic flux quanta.” Physicists believe an as-yet-unseen configuration of such quasiparticles might provide a practical system for achieving “topological quantum computing,” in which quasiparticles on a two-dimensional surface would be able to perform powerful logic operations that obey the particular rules of quantum mechanics.

With this goal in mind, postdoc Yu-Ju Lin, physicist Ian Spielman and the rest of the JQI team have set out to make a gas of neutral atoms behave like electrically charged particles. They couldn’t simply add electric charges to the atoms, or play around with electrons themselves because their mutual electrical repulsion would cause the cloud to fly apart.

In their experiment, they cause a gas of rubidium-87 to form an ultracold state of matter known as a Bose-Einstein condensate. Then, laser light from two opposite directions bathes or “dresses” the rubidium atoms in the gas. The laser light interacts with the atoms, shifting their energy levels in a peculiar momentum-dependent manner. One nifty consequence of this is that the atoms now react to a magnetic field gradient in a way mathematically identical to the reaction of charged particles like electrons to a uniform magnetic field. “We can make our neutral atoms have the same equations of motion as charged particles do in a magnetic field,” says Spielman.

In this first experiment, Spielman and colleagues have effectively “put an electric charge” on atoms, but haven’t “turned on the field.” In subsequent experiments, they plan to introduce an effective magnetic field and watch “electrified” rubidium atoms go on their merry cyclotron ways, with the goal of revealing new insights about the fractional quantum Hall effect and topological computing. Stay tuned!

*More information: Y.-J. Lin, R.L. Compton, A.R. Perry, W.D. Phillips, J.V. Porto and I.B. Spielman, A Bose-Einstein condensate in a uniform light-induced vector potential. Physical Review Letters (forthcoming).

Provided by NIST

Explore further: Online Icicle Atlas offers jackpot of scientific data

add to favorites email to friend print save as pdf

Related Stories

Pebble smartwatch nears Kickstarter record

1 hour ago

The latest version of the Pebble smartwatch neared a record funding amount on Kickstarter on Friday amid growing interest in wearable tech and ahead of the highly anticipated Apple Watch launch.

A molecular compass for bird navigation

2 hours ago

Each year, the Arctic Tern travels over 40,000 miles, migrating nearly from pole to pole and back again. Other birds make similar (though shorter) journeys in search of warmer climes. How do these birds manage ...

Recommended for you

Unified theory for skyrmion-materials

Mar 03, 2015

Magnetic vortex structures, so-called skyrmions, could in future store and process information very efficiently. They could also be the basis for high-frequency components. For the first time, a team of physicists ...

Why seashells' mineral forms differently in seawater

Mar 03, 2015

For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, sometimes take ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

gmurphy
1 / 5 (1) Feb 25, 2009
"One nifty consequence of this is that the atoms now react to a magnetic field gradient in a way mathematically identical to the reaction of charged particles like electrons to a uniform magnetic field", can someone please explain why this is so?
Honor
1 / 5 (1) Feb 25, 2009
cross dressing? what a scandalous title!
menkaur
5 / 5 (1) Feb 26, 2009
it's kind of interesting...
reminds me a bit of an article i've read recently about a scientist discovering monopole in a magic mirror
thewhitelilyblog
1 / 5 (1) Feb 27, 2009
Unnecessary sexual reference. Please.
jonnyboy
1 / 5 (1) Mar 03, 2009
sexual references are always necessary

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.