Shining light on quantum mechanics

By Ben Hoffman

While the phrase “quantum mechanics” alone invokes a panic reaction in nearly anyone who hears it, it’s a surefire thing an entire article about it will be questionably all-encompassing. There’s a stigma attached to the remarkably tiny, remarkably ineffable motes of matter-slash-energy-slash-nonsense–the quanta from which quantum theory derives its name–that their counter-intuitive nature makes them solely the domain of chess-grinding, basement-dwelling math enthusiasts. While there’s certainly no lack of math-love and more than likely at least one chessboard in the black-walled basement laser lab of Canada Research Chair in Experimental Quantum Information and U of C professor Dr. Alex Lvovsky, the man himself speculates that the heady children of Heisenberg and Schrödinger matter more to us than we know. The proof, he assures, is in the processor.

“Our computers get faster because they get smaller,” Dr. Lvovsky said, glancing thoughtfully at his desktop PC and pausing. “Well, not the computers themselves, but the individual transistors, they get smaller and, in fact, they get exponentially smaller, by a factor of two every couple of years.”

Lvovsky was referencing an empirical computer science result called “Moore’s Law,” which has accurately predicted how fast our computers will be since the mid-’60s. Although technical in statement, the law can be roughly viewed as “how much more badass computer games get over time,” or “how much more realistically pervy Uncle Jack’s thin moustache looks in the latest Pixar movie,” and although it seems intuitive that the law will continue to yield successively better anthropomorphic animal movies to further entertain and numb our children, it also predicts some disastrous results.

“The question is, what happens if the trend continues like this for another ten or twenty years?” asked Lvovsky. “The line we extrapolate will get to the size of the individual atom. Then we really get in trouble, because we have to start dealing with elementary particles as carriers of information and elementary particles are governed by totally different laws of physics.”

Lvovsky’s group has been in the news recently for researching these different laws and their repercussions. His group, which studies the technology of the quantum computer–the technology that will replace our own once Moore has led us as far as he can–has recently performed a groundbreaking proof-of-principle experiment demonstrating that one type of this new, strange information can be rassled into holding still for a few microseconds: quantum memory.

“One of our goals is to transport information from one place to another,” said PhD student Eden Figueroa, whose thesis research is on the experiment in question. “The problem is, we want to do it using information that is encoded in the quantum properties of whatever we’re sending–in this case, photons. Since they have these quantum properties, they are very fragile. If you send it through a normal fiber-optic, the properties will disappear. Then, we have to think about the analogy of the repeater in our normal fiber-optic technolo gy to be able to send the information encoded through a long distance. There are several theoretical proposals on how to [do this]. For those proposals, quantum memory is very important.”

“As soon as we cross this boundary from macroscopic to microscopic, from large to small, our whole intuition and experience will become useless,” he said.

Lvovsky explained just how unruly the little smidgens of light can actually be­–so hard a competing group researching the same thing actually gave up.

“It’s like, suddenly you would come to a soccer game and discover that the ball goes through two goals at the same time, or behaves differently just because the audience is watching,” he said. “The quantum world is like this. It’s better, though we aren’t there yet, to prepare ourselves for this future and develop the primitives of quantum information.”

The question, then, is how to make something stay still that has no clear concept of what staying still is. It is a question that Lvovsky, Figueroa and the rest of the group feel they have found at least a partial answer for.

“If you think about memory, you think about something that is static,” said Figueroa. “Light is anything but static–I mean, the speed of light. Another part of our experiment has been learning to address and manipulate atoms. The good thing about atoms is that they can actually stay put. That’s why we combine these technologies. Then, we can start at some point with information in photons and get the same information in the atoms, and be able to release it.”

Though it seems like quantum memory is in sight, there’s still much to do before a full-blown quantum computer lands on our desks. If we use a process similar to our current one, there’s still the processor–far more complicated–to worry about. For the moment though, Lvovsky and Figueroa are content to revel in their success.

“After finishing, we ended up with more questions than answers,” said Figueroa. “For scientists, this fuels them.”


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