Last Updated: December 19, 2001 02:14 PM ET
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By Caroline Humer
NEW YORK, Dec 19 (Reuters) - Researchers at
International Business Machines Corp. IBM.N
said on Wednesday they have demonstrated a calculation that could be
used to break complicated codes, marking a small step in the advance
of quantum computing, a technology based on quantum
mechanics.
IBM scientists
will publish details in the scientific journal Nature on Thursday of
the demonstration of "Shor's Algorithm," a method of factoring
numbers that was developed in 1994 by AT&T T.N
scientist Peter Shor.
It was
that algorithm, and the promise it holds for its ability to break
large encryption codes, that spurred interest in quantum computing
in the 1990s.
Quantum
computing is one of several paths that researchers are taking as
they strive to make smaller and smaller microchips. Under Moore's
Law, which was set forth by Intel Corp. INTC.O
co-founder Gordon Moore, the number of transistors on a chip
doubles, or alternatively, data density doubles, every 18
months.
IBM said it has built
a quantum computer based on seven atoms which, because of the
physical properties of those atoms, are able to work together as
both the computer's processor and memory. Previously the largest
computer IBM had built was based on five atoms.
IBM scientists said that they were able to use the
computer to show that Shor's algorithm works by correctly
identifying 3 and 5 as the factors of 15.
"Although the answer may appear to be trivial, the
unprecedented control required ... during the calculation made this
the most complex quantum computation performed to date," Nabil Amer,
manager of IBM Research's physics of information group said. A
quantum computer is based on the spin of an electron or atomic
nucleus.
In addition to
encryption, other applications for quantum computing include data
mining, or searching large databases for particular pieces of
information. Amer said it is still unclear when quantum computers
could become commercially available.
John Preskill, professor of theoretical physics
and director of the Institute of Quantum Information at CalTech in
Pasadena, California, said that the experiment brought quantum
computing a baby step forward by revealing errors in the
process.
"Part of the
challenge of building large scale quantum computers is that they are
very susceptible to error and we need to understand the types of
errors that occur, as well, in order to know what's the most
promising way of building quantum computers," Preskill said.
To put the size of the computer into
perspective, Preskill explained that currently the fastest computers
in existence, or supercomputers, could factor -- or find the
smallest indivisible factors of -- a number that is 130 digits long
in about a month. But they wouldn't be able to factor a 200-digit
number.
A quantum computer
could tackle that task, he said, but it would need to include
thousands of quantum bits, or atoms. IBM scientists used the
computer based on seven atoms to factor a two-digit number.
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