Amherst Magazine

Quantum Quick

By Peter Rooney

Photo by Rob Mattson

[Tech] What’s faster, a quantum computer or a regular computer? In May, a professor’s attempt to answer this question landed her in the media spotlight.  

Catherine McGeoch
Catherine McGeoch

First, Catherine McGeoch, the Beitzel Professor in Technology and Society, was hired by the Canadian company D-Wave to test the speed of its quantum computing system against conventional computing methods.

As McGeoch prepared to share her findings at a conference in Italy, news outlets came calling: “A Quantum Computer Aces Its Test,” announced a May 8 New York Times headline. Many other publications covered her research, including The Economist and MIT’s Technology Review.

The system she was testing has a thumbnail-sized chip stored in a dilution refrigerator within a shielded cabinet at near absolute zero. Where conventional computing is binary, 1s and 0s get mashed up in quantum computing, and within that super-cooled (and non-observable) state of flux, a lightning-quick logic takes place, capable of solving problems up to 3,600 times as fast as conventional methods, according to her findings.

“Ours is the first paper, to my knowledge, that compares the quantum approach to conventional methods using the same set of problems,” McGeoch says. “I’m not claiming that this is the last word, but it’s a first word.”

McGeoch has 25 years of experience setting up experiments to test computing speed. She is a founder of “experimental algorithmics,” a niche that is increasingly helpful in evaluating computing performance. That’s why she spent a month consulting at D-Wave, which has produced what it claims is the world’s first commercially available quantum computing system.

McGeoch says the D-Wave has the most potential in calculations that involve a specific “combinatorial optimization” problem that is comparable in difficulty to the famous “traveling salesperson” problem. The traveling salesperson problem—foundational to theoretical computing—asks: given a list of cities and the distance between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the original city? The problem can apply to areas such as flight scheduling, search optimization and DNA analysis.

“This type of computer is not intended for surfing the Internet,” McGeoch says, “but it does solve this narrow but important type of problem really, really fast—thousands of times faster than anything I’m aware of.” For other problems, it simply “does as well as some of the best things I’ve looked at.”

But who needs a quantum machine? For now, not the average personal computer user. “It’s probably going to be big companies like Google and government agencies,” McGeoch says.

In fact, Nature reported on May 23 that D-Wave “has secured another customer—a collaboration between Google, NASA and the non-profit Universities Space Research Association.” According to the magazine, “the deal was sealed after” McGeoch’s tests.