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