PWAC Victoria: David Forrest, Writing Sample

The Reading Room

Crazy Computing

by David Forrest © David Forrest 2001

This article describes the paradoxical world of quantum mechanics and some of its startling future applications. Published by the Alliance for Capitalizing on Change, February 2001; republished by Innovation Watch.

Alice laughed. "There's no use trying," she said: "one CAN'T believe impossible things."

"I daresay you haven't had much practice," said the Queen. "When I was your age, I always did it for half-an-hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."

When he wrote these words in Alice's Adventures in Wonderland, Lewis Carroll might just as well have been talking about modern physics. Quantum mechanics--developed in the first decades of the 20th century to describe phenomena at the molecular, atomic and particle level--violates logic and common experience. Paradoxical or not, scientists are applying quantum physics every day to accomplish the impossible, and new experiments in computing show just how weird things will become.

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 is 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.

David Forrest
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Last updated: February 16, 2005 http://www.islandnet.com/pwacvic/forres02.html