Featured Research

from universities, journals, and other organizations

Noisy Pictures Tell A Story Of 'Entangled' Atoms, Physicists Find

Date:
April 19, 2005
Source:
National Institute Of Standards And Technology
Summary:
Patterns of noise—normally considered flaws—in images of an ultracold cloud of potassium provide the first-ever visual evidence of correlated ultracold atoms, a potentially useful tool for many applications, according to physicists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Similar patterns of "noise" are evident in these two images. The images are taken directly after molecules have been split into entangled atom pairs. Each of the pictures shows the absorption of laser light by potassium atoms in one out of two different energy states. High concentrations of atoms absorbing light are circled in yellow, and areas with fewer atoms are circled in green. The similar pattern in the two images directly shows the correlation between atoms in the different states.
Credit: Image courtesy of National Institute Of Standards And Technology

Patterns of noise—normally considered flaws—in images of an ultracold cloud of potassium provide the first-ever visual evidence of correlated ultracold atoms, a potentially useful tool for many applications, according to physicists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Related Articles


Described in the March 21 online issue of Physical Review Letters,* the noise analysis method could, in principle, be used to identify and test the limits of entanglement, a phenomenon Einstein called “spooky action at a distance.” With entangled atom pairs, for example, the properties of one atom instantaneously affect the properties of its mate, even when the two are physically separated by substantial distances. Such tests of the basic rules of quantum physics could be helpful, for example, in efforts to design quantum computers that would use the properties of individual neutral atoms as 1s and 0s for storing and processing data.

The method demonstrated at JILA also could enable scientists to “see,” for the first time, other types of correlations between atoms in fermionic condensates, a new quantum state first created by the same JILA research group (see http://www.nist.gov/public_affairs/releases/fermi_condensate.htm), in which thousands of pairs of atoms behave in unison. And it could perhaps be applied in highly sensitive measurement techniques using beams of entangled atoms.

“There are a number of interesting quantum states that are not obviously seen if you just take a picture,” says Deborah Jin of NIST, leader of the research group that developed the new method and also previously created fermionic condensates. “A Fermi condensate, for example, would not show up in an ordinary image. However, correlations between atoms should actually show up in the noise in these images.”

The noise appears as speckles in images of a cloud of ultracold potassium atoms made under very specific conditions. This noise is not random, as would be expected ordinarily, but rather appears in duplicate patterns suggesting, although not proving, that pairs of atoms are entangled with each other—even when separated by as much as 350 micrometers. (For comparison, a human hair is about 70 micrometers wide.)

In the JILA method, Markus Greiner, Cindy Regal and Jayson Stewart use a laser to trap and cool a cloud of about half a million potassium atoms to near absolute zero temperature. Then a second laser is shined on the atoms, which absorb some of the light, and an image is made of the shadow pattern behind the atoms. The darkest areas have the highest concentrations of atoms that absorb the light. The grainy or dappled pattern of lighter and darker areas represent the so-called “atom shot noise.”

The JILA atom imaging system is designed to minimize other sources of noise, such as from the laser. For instance, the set-up ensures that a relatively large amount of light is captured per pixel (or dot) in the digital image, and that each atom absorbs a relatively large amount of light. In addition, image-processing techniques are used to filter out laser noise and to find the optimal pixel size for “seeing” the noise pattern.

For the experiments, the atoms are prepared in two groups, one at the lowest of 10 possible energy levels in potassium, and the other at the next-lowest energy level. A magnetic field is swept across the trapped mixture of the two groups to combine pairs of atoms of different energy levels into weakly bound molecules. (In this way a molecular version of a Bose Einstein condensate can be created, a state of matter first realized with atoms in 1995 at JILA; see http://www.bec.nist.gov/index.html.) Then the magnetic field is increased to split the molecules and create pairs of atoms that are, based on previous studies and fundamental quantum mechanics laws, known to be entangled.

In one experiment, the JILA team made images of the two groups of atoms separately by tuning the laser to a frequency of light absorbed by only one group at a time. The two images were physically overlaid so that the shot noise in sets of corresponding pixels could be compared. Using mathematical techniques to analyze the images, the scientists found similar patterns of dark and light areas, clear evidence for correlated atoms.

In a second experiment, scientists split the molecules with a radio wave pulse into pairs of entangled atoms flying apart with equal momentum but in opposite directions. The scientists again took images of each set of atoms and overlaid them. But this time, they systematically rotated one image to check for correlations in noise patterns. Similar patterns were found after a 180-degree rotation, in pixels on opposite sides of the cloud, clearly indicating correlated atom pairs. In this experiment the atom pairs are detected as far as 350 micrometers apart, and as a result fascinating quantum phenomena like the “spooky action at a distance” could be studied.

The research was supported in part by the National Science Foundation and National Aeronautics and Space Administration.

As a non-regulatory agency of the U.S. Department of Commerce’s Technology Administration, NIST develops and promotes measurement, standards and technology to enhance productivity, facilitate trade and improve the quality of life.

###

*M. Greiner, C.A. Regal, J.T. Stewart, and D.S. Jin. 2005. Probing Pair-Correlated Fermionic Atoms through Correlations in the Atom Shot Noise. Physical Review Letters, posted online March 21, 2005.


Story Source:

The above story is based on materials provided by National Institute Of Standards And Technology. Note: Materials may be edited for content and length.


Cite This Page:

National Institute Of Standards And Technology. "Noisy Pictures Tell A Story Of 'Entangled' Atoms, Physicists Find." ScienceDaily. ScienceDaily, 19 April 2005. <www.sciencedaily.com/releases/2005/04/050411203310.htm>.
National Institute Of Standards And Technology. (2005, April 19). Noisy Pictures Tell A Story Of 'Entangled' Atoms, Physicists Find. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2005/04/050411203310.htm
National Institute Of Standards And Technology. "Noisy Pictures Tell A Story Of 'Entangled' Atoms, Physicists Find." ScienceDaily. www.sciencedaily.com/releases/2005/04/050411203310.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins