As I blog on Dr. Dobb's CodeTalk for computer programmers about Quantum Computing, the burning question in my mind, and the question in my readers' (and editors') minds is

"When are these devices going to be practical so we can play with them!?"

I'm beginning to have a inkling what is the answer to that question ...

There are theoretical problems in creating practical quantum computing. Having shown readers the one-dimensional ion trap quantum computing experiment I'll be writing later in this series about the next level theoretical challenge, maintaining webs of computable quantum entities in two dimensions. But even as the theoretical problems are mowed down one at a time, the engineering challenges to building practical devices remain awesome and much less tractable than the theoretical problems.

The folks working on quantum computing today are pretty much all physicists: a few are "mere" engineers and essentially none are "just programmers". It seems to me ... and here I'm sorta whistling in the dark .. that the emphasis in quantum computing efforts is often on the quantum mechanical aspects. The researchers may tend to view quantum computing as an application of quantum mechanics rather than quantum mechanics as a discipline for achieving quantum computing.

This reminds me of another long-ago dialectic between theoretical physics and practical engineering ... the invention of the incandescent lightbulb.

The great theoretical physicists in electricity of the late 1800's were all in England, and were unanimous on one point: having seen the arc light, they were convinced that the incandescent lightbulb, when finally achieved, would be a high-amperage device. To this end, they were twisting copper wire and running high current through it, and true, these devices could be made to glow cherry-red.

American home-schooled grammar-school dropout Thomas Alva Edison said, "Horsefeathers!" He began the search for the low-amperage incandescent device. He put fifty tables in a long workshop and put two technicians at each table and handed out a list of 500 materials he though might provide a filament, and set his hireling techs at it by rote. When they got to the convection-carbonized bamboo Edison's field agents had brought back from Malaya, they had a lightbulb (and, unbeknownst to Edison, the vacuum tube and quantum physics as well, though the stains on the globe from carbon atoms fleeing the filament in a quantized vector defied his explanation at the time).

So I suspect that the answer to "Quantum Computers -- When?" is this: When a critical mass of pratical engineers and technicians in pursuit of filthy lucre are willing and able work on the problem alongside the quantum physicists, we'll start to see some real progress.

Some young readers of Dr. Dobb's CodeTalk will probably be among those who make that happen. Get busy! I want a quantum computer to play with before I'm too old to enjoy it!