Last August, IBM announced that it had built and tested
an experimental quantum computer based on fluorine atoms
that found the solution to a complex problem in a single
step. Isaac Chung, leader of IBM’s research team, announced
that similar devices built on a larger scale could take
only days to solve mathematical problems that would require
millions of years for a conventional computer to solve.
Hybrids between conventional and quantum computers might
be possible within five years, he said.
While an 8-bit digital computer can be in only one of 256
states at any given time, an 8-bit quantum computer is in
all 256 states simultaneously, and in principle can work
on 256 calculations at once. The more bits used, the more
calculations that can be done simultaneously, and the faster
the machine. Building a machine with 40 quantum bits (qubits)
would allow more than a trillion calculations to be performed
at the same time.
While that may sound weird, it’s child’s play compared
to the spooky world of quantum entanglement. When a laser
beam is shined through a special crystal, two beams emerge
on the other side as each photon in the original beam is
split into two. And while the two resulting photons in the
emerging beams are separated by distance, they remain aware
of each other’s existence. Any subsequent change in one
instantaneously produces a complementary change in the other,
even though they may be miles apart at the time.
In 1997, scientists at the University of Geneva demonstrated
that entangled particles of light could communicate over
a distance of 7 miles. When the spin of one photon was changed
after two beams were sent down separate fiber-optic cables,
the other photon instantaneously made a corresponding change.
Physicists at Los Alamos National Laboratory in New Mexico
have successfully applied quantum entanglement to cryptography,
using protons to transmit a cryptographic key over a distance
of 30 miles. Interception can be detected through observing
missing protons, and eavesdropping can be identified through
a change in quantum states.
Using quantum entanglement, in 1997 researchers at the
University of Innsbruck successfully transmitted information
on the state of a quantum system, and replicated it in another
place – a feat that has come to be known as ‘quantum teleportation.’
In 1998 scientists at the California Institute of Technology
refined the experiment and repeated it with greater accuracy.
While teleportation can theoretically be used to replicate
a system across an infinite distance, it will most likely
be used to move data within quantum computers. And while
it is theoretically possible, the ‘teleportation’ of large
objects is practically unachievable, at least for now.
This new science seems incomprehensible and irrational,
even to many of the scientists themselves. Erwin Schrodinger,
who helped to develop the foundations of quantum physics,
lamented in the end, “I don’t like it, and I’m sorry I ever
had anything to do with it.” Like it or not, it appears
that we are soon going to apply it in unexpected ways. We
will all have to live with it, and it will fundamentally
change our lives.
RESOURCES:
California Institute of
Technology
http://corporate.caltech.edu/forefronts/Quantum.html
IBM Corporation – Quantum
Computing
http://www.research.ibm.com/resources/news/20000815_quantum.html
IBM Corporation - Quantum
Teleportation
http://www.research.ibm.com/quantuminfo/teleportation/
The Stanford-Berkeley-MIT-IBM
MNR Quantum Computation Project
http://squint.stanford.edu
