By Jack Ganssle

Quantum Puzzlement

Published 8/7/2006

Researchers at the University of Illinois (http://www.newscientisttech.com/article/mg18925405.700.html ) have created a quantum computer that returns an answer when the machine isn't turned on.

After reading this I turned my PC off, but somehow all work ceased. Email no longer flooded in, and quantum vacuum fluctuations didn't make this article pop into existence.

Even better, those pesky Windows bugs might all disappear. The article makes the thoughtful point that a machine that's off exhibits fewer bugs. Well, duh! But on further thought one realizes that only a machine that's on can crash. Remove the power and all of our programs become perfect.

Quantum computing has become a hot topic. Scientists are slinging qubits around in all sorts of ways that will apparently greatly simplify both code-breaking and cryptography. If they can get the technology to work well, monster searches and massively-parallel problems may no long consume much computer horsepower. The possibilities (see http://money.cnn.com/2006/07/26/magazines/fortune/futureoftech_quantum.fortune/index.htm ) are tremendously exciting.

And also baffling.

How can a computer work at all when it's turned off?

As I understand the promise, a small quantum register can store an enormous range of numbers, all simultaneously. So it takes very little "hardware" (whatever that looks like) to represent pretty much every possible solution to a problem. But the details of presenting a problem to even a single qubit machine, and getting an answer, sure are puzzling.

Even Richard Feynman, who laid out the physics of quantum electrodynamics, said that anyone who claims to understand quantum mechanics, doesn't.

Though that makes me feel a little less ignorant, I do wonder how normal engineers and programmers, who don't have the letters "Phd" appended to their names, will be able to use these machines.

Perhaps physicists will develop an API that masks the inscrutable details of their quantum computers. In one sense we're already buffered by a similar interface; none of us need to understand tunneling to use an EPROM, nor do we have to master Schr”dinger's wave equation to shepherd electrons through a circuit. Our level of abstraction from the quantum mechanics of electronics is nearly complete, in that we assemble circuits using physically-large ICs which encapsulate all sorts of sub-atomic behavior.

Wikipedia has a pretty clear article (http://en.wikipedia.org/wiki/Quantum_computing ) on the quantum computing. Though I have no idea if practical computers will ever result from this research, the possibilities are tremendously exciting.

What do you think? Going back to school to manipulate quarks and gluons?