Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists Measure Tiny Force That Limits How Far Machines Can Shrink

26.09.2005


This simple sketch shows the placement of diffraction gratings - represented by the vertical dashed lines - that split and recombine atom waves. The gratings are about a meter apart.


University of Arizona physicists have directly measured how close speeding atoms can come to a surface before the atoms’ wavelengths change.

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.

Lori Stiles | EurekAlert!
Further information:
http://www.arizona.edu

More articles from Physics and Astronomy:

nachricht Tune your radio: galaxies sing while forming stars
21.02.2017 | Max-Planck-Institut für Radioastronomie

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>