Electronic Circuits Scale Down
Source: BBC News Sci/Tech
Scientists at IBM say they have made a breakthrough which could
make it possible to create electronic circuits that can be measured in
nanometres - just billionths of a metre across.
The company's research division at San Jose, California, has
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 Eigler, the lead researcher on the project.
"We call it a mirage because we project information about one atom
to another spot where there is no atom."
As electronic circuits get smaller and smaller, the behaviour of
electrons changes from being particle-like, and described by classical physics,
to being wave-like and described by quantum mechanics.
On very small scales, tiny wires do not conduct electrons very
well. So quantum equivalents for many traditional functions must be available if
nanocircuits are to achieve the desired performance.
But to do this, scientists must learn how to manipulate the
strange behaviour of the quantum world.
Quantum corral
To create the quantum mirage, the IBM scientists built a ring of
cobalt atoms on a copper surface. The ring of atoms acts 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 corral determines the energy states and
spatial distribution of the confined electrons. When the IBM scientists placed
an atom of magnetic cobalt at one point in the ring, a mirage appeared at
another point. The scientists say they detected the same electronic states in
the copper electrons surrounding the phantom cobalt atom, even though no
magnetic atom was actually there.
The intensity of the mirage was about one-third of the intensity
around the "real" cobalt atom.
The operation of the quantum mirage is similar to the way in which
light or sound waves are focused to a single spot by optical lenses, mirrors,
and parabolic reflectors.
The experiments were imaged using the extraordinary power of the
scanning tunneling microscope, the same instrument that enabled researchers to
drag individual atoms into the shape of the IBM corporate logo 10 years ago.
Details of the research have been published in the journal Nature.
Gigahertz race
In a separate announcement, IBM says it will shortly unveil a new
family of high-speed computer circuits that run at speeds of 3.3 to 4.5
gigahertz, up to five times faster than today's fastest Pentium III chips.
The new design employs conventional silicon transistors, but uses
only half the power of a standard high-performance chip.
"Not only are we in the gigahertz era of microprocessors, but we
see our way clear to three to four gigahertz in the future," said Randall Isaac,
vice president of systems, technology and science at IBM Research.
"One gigahertz will be commercially available within one year -
three and four gigahertz will take three to four years to be commercially
available."
Not to be outdone, Intel Corp, the world's largest computer chip
maker, says its one gigahertz processors will be available commercially even
sooner than IBM's technology - probably within the next 12 months.
February 8, 2000