Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Physicists Measure Tiny Force That Limits How Far Machines Can Shrink


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

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:

More articles from Physics and Astronomy:

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Innovative technique for shaping light could solve bandwidth crunch
20.10.2016 | The Optical Society

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>