Theos-Talk Archives (July 2001 Message tt00057)

Interesting in that it is promoting an image from a central core.

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"Quantum Mirage" May Enable Atom-scale Circuits; IBM Scientists Discover 
Nanotech Communication Method


SAN JOSE, Calif., February 2, 2000 -- IBM scientists have discovered a way to 
transport information on the atomic scale that uses the wave nature of 
electrons instead of conventional wiring. 
The new phenomenon, called the "quantum mirage" effect, may enable data 
transfer within future nanoscale electronic circuits too small to use wires.

"This is a fundamentally new way of guiding information through a solid," 
said IBM Fellow Donald M. Eigler, IBM's lead researcher on this project.. "We 
call it a mirage because we project information about one atom to another 
spot where there is no atom."

As computer circuit features shrink toward atomic dimensions -- which they 
have for decades in accordance with Moore's Law -- the behavior of electrons 
changes from being like particles described by classical physics to being 
like waves described by quantum mechanics. On such small scales, for example, 
tiny wires don't conduct electrons as well as classical theory predicts. So 
quantum analogs for many traditional functions must be available if 
nanocircuits are to achieve the desired performance advantages of their small 
size.

IBM's new quantum mirage technique may prove to be just such a substitute for 
the wires connecting nanocircuit components.

The quantum mirage was discovered by three physicists at IBM's Almaden 
Research Center here: Hari C. Manoharan, Christopher P. Lutz and Eigler. They 
reported their findings in the cover story of the February 3, 2000, issue of 
Nature, a prestigious international scientific journal published in London. 
They used the same low-temperature scanning tunneling microscope (STM) with 
which Eigler and Erhard Schweizer first positioned individual atoms 10 years 
ago, spelling out the letters I-B-M with 35 xenon atoms.

To create the quantum mirage, the scientists first moved several dozen cobalt 
atoms on a copper surface into an ellipse-shaped ring. As Michael Crommie 
(who is now a professor at the University of California-Berkeley), Lutz and 
Eigler had shown in 1993, the ring atoms acted as a "quantum corral" -- 
reflecting the copper's surface electrons within the ring into a wave pattern 
predicted by quantum mechanics.

The size and shape of the elliptical corral determine its "quantum states" -- 
the energy and spatial distribution of the confined electrons. The IBM 
scientists used a quantum state that concentrated large electron densities at 
each focus point of the elliptical corral. When the scientists placed an atom 
of magnetic cobalt at one focu, a mirage appeared at the other focus: the 
same electronic states in the surface electrons surrounding the cobalt atom 
were detected even though no magnetic
atom was actually there. The intensity of the mirage is about one-third of 
the intensity around the cobalt atom.

"We have become quantum mechanics -- engineering and exploring the properties 
of quantum states," Eigler said. "We're paving the way for the future 
nanotechnicians."

The operation of the quantum mirage is similar to how light or sound waves is 
focused to a single spot by optical lenses, mirrors, parabolic reflectors or 
"whisper spots" in buildings. For example, faint sounds generated at either 
of the two "whisper spots" in the Old House of Representatives Chamber (now 
called Statuary Hall) in the U.S. Capitol Building in Washington, D.C., can 
be heard clearly far across the chamber at the other whisper spot.

"The quantum mirage technique permits us to do some very interesting 
scientific experiments such as remotely probing atoms and molecules, studying 
the origins of magnetism at the atomic level, and ultimately manipulating 
individual electron or nuclear spins," said Dr. Manoharan. "But we must make 
significant improvements before this method becomes useful in actual 
circuits. Making each ellipse with the STM is currently impractically slow. 
They would have to be easily and rapidly produced, connections to other 
components would also have to be devised and a rapid and power-efficient way 
to modulate the available quantum states would need to be developed."

The IBM scientists have built and tested elliptical corrals up to 20 
nanometers long with the width as little as half that. (A nanometer is one 
billionth of a meter -- about 40 billionths of an inch -- or about the size 
of a five atoms placed side-by-side.) The electron density and intensity of 
the mirage depends on the quantum state, not the distance between the foci.

IBM Research has long been a leader in studying the properties of materials 
important to the information technology industry. In 1981, Gerd Binnig and 
Heinrich Rohrer of IBM's Zurich Research Laboratory in Switzerland invented 
the scanning tunneling microscope, which enabled scientists to see -- and in 
1990, position -- individual atoms. For this achievement, they shared the 
1986 Nobel Prize in Physics. In 1984, Binnig co-invented the Atomic Force 
Microscope, which led to a variety of new instruments that used various tiny 
cantilevers to extend near-atomic resolution imaging to many to many new 
forces, including friction and magnetism. IBM's Almaden (San Jose, Calif.), 
Watson (Yorktown Heights, N.Y.) and Zurich (Switzerland) laboratories 
continue active and complementary nanotechnology research efforts.

IBM Research operates in eight locations worldwide: the Thomas J. Watson 
Research Center in Yorktown Heights, NY; the Almaden Research Center in San 
Jose, Calif.; the Zurich Research Laboratory in Zurich, Switzerland; the 
Tokyo Research Laboratory in Yamato, Japan; the Haifa Research Laboratory in 
Haifa, Israel; the China Research Laboratory in Beijing, China, the Austin 
Research Laboratory in Austin, Texas, and the India Research Center in Dehli, 
India.

For more information on IBM Research, please visit the Website at: 
http://www.research.ibm.com

Dramatic electronic images showing the quantum mirage are available at: 
http://www.almaden.ibm.com/almaden/media/image_mirage.html