Man this is some trippy toejam. Gotta get me one nuclear magnetic resonance spectrometer...
(full article no link givin)
SCIENCE
Efforts to Transform Computers Reach Milestone
By GEORGE JOHNSON
In an important milestone toward making powerful computers that exploit the
mind-bending possibilities of calculating with individual atoms, scientists
at the I.B.M. Almaden Research Center, in San Jose, Calif., are announcing
today that they have performed the most complex such calculation yet:
factoring the number 15.
The answer itself was no surprise: 3 and 5, the numbers that divide into
15,leaving no remainder. But the exercise that led to that simple result -
the first factoring of a number with an exotic device called a quantum
computer - holds the promise of one day solving problems now considered
impossible, and cracking seemingly impenetrable codes.
Tiny though they are, the switches that manipulate ones and zeroes in
currentstate-of-the-art computers each consist of billions of atoms. In the
quantum computing experiment, the scientists performed the calculation by
manipulating single atoms, the submicroscopic equivalent of abacus beads.
This confirmed a big advantage: because of the chimerical nature of quantum
mechanics, the law that rules the atomic realm, the procedure's multiple
steps could be carried out simultaneously.
If this kind of quantum parallelism can be extended to a larger scale, an
effortfar from trivial, numbers hundreds of digits long could be factored
with ease. Since many schemes used to protect electronic information are
based on thenear impossibility of factoring large numbers, building a
working quantum computer would be not only a mathematical coup but a
cryptographic one as well, potentially putting much of the world's most
secret information in jeopardy.
"We now believe that quantum computing is going to be a fact of nature,"
said Dr. Isaac L. Chuang, who led the team of researchers, from I.B.M. and
Stanford University. "That's incredibly surprising to me. I started out
thinking that quantum computing was not going to be a viable enterprise."
He said he was happy to have been proved wrong.
Dr. Peter Shor, the scientist at AT&T Laboratories who proved seven years
ago that quantum factoring was a theoretical possibility, called the new
advance, being reported today in the journal Nature, "an impressive
accomplishment," though he added, "There's still a long road ahead before
we develop useful quantum computers."
Factoring is what mathematicians call an intractable problem. It is easy to
factor small numbers, but as they increase in size, calculation time grows
exponentially. In 1999, experts set a record by factoring a 155-digit
number - a feat that required 292 computers grinding away for half a year.
Because of the exponential nature of the problem, factoring a number twice
that longcould take hundreds of millions of years.
Cryptographers have drawn on this fact to develop codes considered all but
unbreakable. The sender of a message picks two long prime numbers (those
that have no factors) and multiplies them together. This yields a larger
number that becomes the key used to encrypt the text. Breaking the code
entails working backward to recover the original factors, a procedure
requiring enough calculations to flummox a supercomputer.
Quantum computing, however, works by different rules. In 1994, Dr. Shor
invented an algorithm - a sequence of operations - that would allow a
quantum computer to do the calculations simultaneously, factoring
numbershundreds of digits long in perhaps minutes.
This is possible because a quantum computer's counters consist of single
atoms, which can point up or down, indicating 1 or 0, the two symbols of
binary arithmetic. More important, quantum mechanics allows an atom to
point both up and down simultaneously, indicating 1 and 0 at the same time.
Thus two atoms can simultaneously register four quantities: 00, 01, 10 and
11 (the numbers 0 through 3 in the binary tongue). Three atoms can hold
eight numbers, four can hold 16. By the time you reach seven atoms - the
number harnessed for the I.B.M. experiment - you have a tiny device with
the capability of simultaneously registering 128 different numbers.
Flipping the atoms up and down in various patterns causes a calculation to
be performed - on all the numbers at once.
In the experiment, Dr. Chuang and his colleagues - Dr. Lieven M. K.
Vandersypen, Matthias Steffen, Gregory Breyta, Dr. Costantino S. Yannoni
and Dr. Mark H. Sherwood - used a molecule consisting primarily of fluorine
and carbon atoms.
A vial of liquid containing quadrillions of the molecules was placed inside
a machine called a nuclear magnetic resonance spectrometer, using the same
technology on which hospitals draw for M.R.I. scanning. By bombarding the
molecules with a precise sequence of electromagnetic pulses, the
experimenters carefully flipped the atoms back and forth between 1 and 0,
carrying out the steps of Dr. Shor's algorithm.
Rapidly factoring numbers the size of those used in cryptography would
probably require delicate manipulation of tens of thousands of atoms, and
the slightest disturbance could cause the calculation to come undone. But
with the principle of quantum factoring proved on paper and now
demonstrated in the laboratory, some scientists are optimistic.
"We have to move far beyond this," Dr. Chuang said. "But at least we
havedemonstrated that it is possible."
