Featured Research

from universities, journals, and other organizations

Physicists Measure Tiny Force That Limits How Far Machines Can Shrink

Date:
September 24, 2005
Source:
University of Arizona
Summary:
University of Arizona physicists have directly measured how close speeding atoms can come to a surface before atom wavelengths change. Their research has huge implications for nanotechnology and atom optics.

Alex Cronin (left) and John Perreault make an adjustment on the atom interferometer that they used in making the first direct measurement of atom wavelength shift caused by the van der Waals interaction.
Credit: Image courtesy of University of Arizona

Theirs is a first, fundamental measurement that confirms the idea that the wave of a fast-moving atom shortens and lengthens depending on its distance from a surface, an idea first proposed by pioneering quantum physicists in the late 1920s.

The measurement tells nanotechnologists how small they can make extremely tiny devices before a microscopic force between atoms and surfaces, called van der Waals interaction, becomes a concern. The result is important both for nanotechnology, where the goal is to make devices as small as a few tens of billionths of a meter, and for atom optics, where the goal is to use the wave nature of atoms to make more precise sensors and study quantum mechanics.

UA optical sciences doctoral candidate John D. Perreault and UA assistant professor of physics Alexander D. Cronin report the experiment in the Sept. 23 Physical Review Letters. The paper is online at http://xxx.lanl.gov/PS_cache/physics/pdf/0505/0505160.pdf

Perreault and Cronin used a sophisticated device called an atom interferometer in making the measurement. Cronin brought the 12-foot-long device to UA from MIT three years ago. The atom interferometer was assembled over 15 years with more than $2 million in research grants from the National Science Foundation, the UA and the Research Corp. Now in Cronin's laboratory on the third floor of the UA's Physics and Atmospheric Sciences Building, the machine is one of only a half-dozen such instruments operating in the United States and Europe. It splits and recombines atom waves so that scientists can observe the position of the wave crests.

"Our research provides the first direct experimental evidence that a surface 25 nanometers away (25 billionths of a meter) causes a shift in the atom wave crests," Perreault said. "It shows that the van der Waals interaction may be a small scale force, but it's a big deal for atoms."

Perreault and Cronin found that atoms closer than 25 nanometers to a surface are very strongly attracted to the surface because of the van der Waals interaction-- so strongly that the atoms are accelerated with the force of a million g's.

A "g" is a term for acceleration due to gravity. One g is an everyday experience -- it's the force a person feels from Earth's gravity. A roller coaster rider might feel 3 to 4 g's for brief moments during a ride. Fighter pilots can experience accelerations of up to 8 g for brief periods during tactical maneuvers, but can black out if subjected to 4 to 6 g's for more than a few seconds.

"We might say that when an atom is between 10 and 20 nanometers from a surface, it gets sucked toward the surface with a force a million times its weight," Cronin said. "And when it gets closer, it gets pulled even harder."

The momentary acceleration of the atom as it passes by the surface is expressed in a famous equation which relates the speed of an atom to its wavelength, Cronin said. When atoms are accelerated and closer to the surface, their wavelengths become shorter. When farther from a surface, atoms return to their original wavelength. Perreault and Cronin used the atom interferometer to measure the wavelength shift.

Nanotechnology research aims to build much smaller transistors and motors, for example, than currently exist. Atom optics research aims to exploit the wave behavior of atoms in ways that will make more precise gyroscopes for navigation, gravity gradiometers for subterranean mapping and other field sensors.

"I think the impact of our work stems from the intersection of the fields of atom optics and nanotechnology," Perreault said. "It answers the question of how far you can miniaturize an atom optics device - for example, a device that guides atoms on a chip to form a very tiny interferometer - before this nano-interaction disrupts operations."

The idea that atoms behave as waves as well as particles goes back to 1924. They're called "de Broglie waves" for early 20th-century French quantum physicist Prince Louis-Victor de Brogli, who first proposed the concept of atom waves. Scientists have grappled with the dual wave-particle nature of atoms for decades and, in the 1990s, they began chilling atoms to near absolute zero and studying the wave properties of atoms in detail.


Story Source:

The above story is based on materials provided by University of Arizona. Note: Materials may be edited for content and length.


Cite This Page:

University of Arizona. "Physicists Measure Tiny Force That Limits How Far Machines Can Shrink." ScienceDaily. ScienceDaily, 24 September 2005. <www.sciencedaily.com/releases/2005/09/050923154827.htm>.
University of Arizona. (2005, September 24). Physicists Measure Tiny Force That Limits How Far Machines Can Shrink. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2005/09/050923154827.htm
University of Arizona. "Physicists Measure Tiny Force That Limits How Far Machines Can Shrink." ScienceDaily. www.sciencedaily.com/releases/2005/09/050923154827.htm (accessed April 20, 2014).

Share This



More Matter & Energy News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Why Did Nike Fire Most Of Its Nike FuelBand Team?

Why Did Nike Fire Most Of Its Nike FuelBand Team?

Newsy (Apr. 19, 2014) Nike fired most of its Digital Sport hardware team, the group behind Nike's FuelBand device. Could Apple or an overcrowded market be behind layoffs? Video provided by Newsy
Powered by NewsLook.com
Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
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:
from the past week

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