Intelligent Machines

R&D 2002: Quantum Computing

Microsoft Research’s theoretical mathematics program breaks the mold with research into a strategy to make quantum computing work.

Populated by programmers worrying about fixes for the latest operating systems and rollouts of new applications, a software company might seem an odd place for rethinking the very foundations of computation. But at Microsoft Research, Michael Freedman is doing just that. One of the world’s most heralded mathematicians and a 1986 winner of the Fields Medal-math’s equivalent of a Nobel Prize-Freedman is spending his days pondering one of the toughest puzzles in physics: how to transform quantum computing from an abstract dream into a feasible technology. And he believes he may have found a solution.

For decades, physicists have speculated that quantum computers would define the ultimate limits for speed, size, and power in computers. The peculiar laws of quantum mechanics dictate that a “quantum bit” has almost magical computing potential. While the digital bits stored in a desktop computer correspond to either ones or zeroes, quantum bits-sometimes represented in the spin of nuclei or ions-can be both ones and zeroes simultaneously. Even odder, quantum bits are linked by a phenomenon called “entanglement.” Together, these properties mean that a computational operation on one quantum bit affects others, implying potentially awesome computing power. In theory at least, quantum computers will need only microseconds to crack even the most sophisticated encryption codes and will be able to search petabyte databases in a flash.

“The idea is to store a bit of information on each atom,” says MIT quantum computer researcher Seth Lloyd. “It’s the logical endpoint of Moore’s Law.”

This story is part of our December 2002/January 2003 Issue
See the rest of the issue
Subscribe

At this nanoscopic scale, however, the world is anything but logical. For those hoping to build a quantum computer, that is both good and bad, and it’s where Freedman’s work comes in. Specifically, he’s trying to solve a problem that has bedeviled quantum computing researchers seeking a way to store information in the spin of nuclei or ions: even the slightest disturbance scrambles the quantum bits and destroys their entanglement. Topology, Freedman’s brand of abstract math, might provide the answer. Topologists worry about the qualities of geometric shapes rather than quantities such as size: the way strands of a knot are entwined is more important than how big the knot is. And Freedman believes that if quantum bits were based on topology, they would be far more robust.

To visualize how this might work, put three marbles on a table and scoot them around. If you were able to keep track of and record the position of the marbles over time, their three paths might eventually trace a “braid.” Freedman imagines that his computer would be made of special “quasiparticles” found in exotic materials such as superconductors that “remember” where they have been. These particles might be braided or arranged using electric fields, and the shape of the braid would be used to represent data. Unlike other quantum bits, however, these quantum braids would be less vulnerable to external disturbances because their shapes would be robust.

Freedman’s work doesn’t stop with out-of-this-world thought experiments. He’s looking for a real material that can perform these topological tricks. “I’m a pure mathematician transitioning into materials designer,” he says. To help him, Freedman has recruited researchers with materials experience onto his team. Working together, they hope both to design and to fabricate a substance that has all the right properties for supporting error-free quantum computing.

This project, of course, marks quite a departure for Microscoft, a company associated with word processing software and desktop computing-not materials science or basic physics. For one thing, it will likely be decades before quantum computing becomes feasible, if it ever does. And for another, if Freedman is right, his advance will signal a quantum jump in computing that will make almost everything Microsoft does obsolete. “My fantasy,” says Freedman, “is that Bill Gates can get up someday and say Microsoft introduced the quantum computer and a software revolution at the same time.”

Become an MIT Technology Review Insider for in-depth analysis and unparalleled perspective.

Subscribe today

Uh oh–you've read all of your free articles for this month.

Insider Premium
$179.95/yr US PRICE

More from Intelligent Machines

Artificial intelligence and robots are transforming how we work and live.

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Premium {! insider.prices.premium !}*

    {! insider.display.menuOptionsLabel !}

    Our award winning magazine, unlimited access to our story archive, special discounts to MIT Technology Review Events, and exclusive content.

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

    First Look: exclusive early access to important stories, before they’re available to anyone else

    Insider Conversations: listen in on in-depth calls between our editors and today’s thought leaders

  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus ad-free web experience, select discounts to partner offerings and MIT Technology Review events

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning magazine and daily delivery of The Download, our newsletter of what’s important in technology and innovation.

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

/
You've read all of your free articles this month. This is your last free article this month. You've read of free articles this month. or  for unlimited online access.