Quantum Computers, Part 1: A Simple Understanding
Nov 2, 2011 5:00 AM PT
Good luck finding a nice, clean entry point to discuss quantum computers.
It should come as no surprise, of course, that something called "quantum computers" would be tricky to talk about. The inner workings of computers are plenty complex to begin with. When melded with a dizzying branch of physics -- quantum mechanics, which dissects the world of atomic and sub-atomic movement -- the result is bound to defy simplistic explanations.
For the laymen among us, quantum technology is so daunting that simply asking someone to explain it can be complicated. I learned, for instance, that sending an interview request to a quantum physicist is liable to come back thus: "Please try me anytime next week if you're happy with a non-unit probability of successfully getting through."
But even if quantum computers require an expanded vocabulary and understanding of mind-bending science, their impact moving forward figures to be incalculable. (Incalculable here is used literally.) Researchers, engineers and, importantly, investors have dived in headlong at companies like IBM and D Wave, and at universities from California to Denmark. What's more, companies like Nokia and Lockheed Martin have begun to meld quantum technology into their operations, thus proving that the steady migration from labs to commercial industry is under way.
Indeed, quantum computers are not some sci-fi theory residing only in the future. They're part of the here and now, and they will be ever more so over the coming years -- even if many of those who stand to gain have a non-unit probability of understanding exactly how they work.
For someone who would have plenty of trouble calculating even a simple physics problem (like the author), analogies can help make sense of the perplexing quantum world. Alas, even analogies are profoundly imperfect, for anything that invokes the non-quantum world (the world we see) to explain the quantum world (the world we don't) is inherently flawed.
"Our heads have evolved over the millennia to deal with things we can understand," said quantum researcher Jeremy O'Brian, who is a professor of physics and electrical engineering at Bristol University.
"Quantum physics would be absolutely obvious to us if we traveled the speed of light or moved like electrons," he told TechNewsWorld. "All of this stuff would make sense and we could totally get our heads around this. But it's just not how we've evolved. We evolved to understand regular physics, so this stuff can seem bizarre."
As such, it may be best to start with something else that once seemed entirely bizarre: the laser.
In 2010, O'Brien coauthored a paper that appeared in the science journal Nature, a paper that used lasers as a springboard to quantum technology. (The section about lasers was one of the few not written in quantumese, which tends to read something like: "Faster nanostructred NbN superconducting nanowire detectors have achieved high efficiency and photon number resolution ...")
Before lasers, there had already been myriad technological advancements with light. The candle evolved into a lantern, the lantern into a light bulb, the light bulb into a flashlight and so on.
But none of these technologies, the paper explains, were "coherent." Light was generated and then dispersed from the source. End of story.
The laser, however, is different because it is "coherent light," not emitted and then forgotten but instead manipulated to perform a function. This coherence means that lasers can perform surgeries and scan bar codes and do any number of things that its predecessors couldn't. It is like light that thinks.
Not Replacing, but Reinventing
Even so, lasers didn't replace light bulbs and candles. They were instead a supplement, not designed to supplant existing technology, but to aid in the situations when a lantern wouldn't cut it.
And this is what's happening, roughly, with quantum computers. People aren't attempting to reinvent classical computers, just as the people who built the laser weren't attempting to reinvent the flashlight. Instead, they're building an entirely different type of computer.
"We're not trying to compete with conventional computers that perform conventional functions," Geordie Rose, chief technology officer at the quantum computer manufacturer D Wave, told TechNewsWorld. "The things they're good at, they're really good for. But there are many things computers aren't good at."
These shortcomings are where quantum technology comes into play. And people around the world have embarked on a quest to fill the voids.
"There's a lot of optimism that we can build more and more complexity in the computers," said John Martinis, a physics professor at the University of California, Santa Barbara.
"The problem with quantum computing is that you have to compete with something" -- modern-day computers -- "that is so utterly fantastic," he told TechNewsWorld.
But as the march down the path of quantum computing continues, the definition of "utterly fantastic" figures to be rewritten. To some extent, it already has been.