MITRE | The MITRE Digest | MITRE and Princeton Go Quantum Together

Home > News & Events > MITRE Publications > The MITRE Digest >

MITRE and Princeton Go Quantum Together

February 2008

View PDF of this article

Email link to this article

The research pace in the quest for a quantum computer has garnered some hefty attention lately, and with good reason. Better understanding of quantum effects and some surprising advances in quantum prototyping have contributed to sizable growth in the field. And it's a global effort: more governments and multinationals are investing heavily in an outcome that could forever revolutionize information processing.

None of this surprises MITRE's Gerry Gilbert, who began his research at MITRE in 1996—two years after Peter Shor's discovery of the first-ever quantum algorithm for factoring large numbers. Gilbert, who earned his doctorate in theoretical physics under Nobel Laureate Steven Weinberg, now directs MITRE's Quantum Information Science (QIS) Group in Eatontown, New Jersey. The real surprise for Gilbert was the telephone call he got from one of the country's leading theorists in particle physics and string theory, Curtis Callan, the director of the new Princeton Center for Theoretical Physics. (For more, see "A Major Effort Starts Small," below.)

Callan explained that his plan was to create an opportunity for scientists to "collaborate on key problems intersecting many disciplines." This is especially relevant because an unusual number of Princeton faculty, trained as theoretical physicists, actually work in other disciplines like chemistry, engineering, molecular biology, and genomics. The idea behind the Center for Theoretical Physics is to bring everyone together in one place. Coincidentally, the MITRE QIS Group's work in quantum computation aligned perfectly with the Center's first-year research theme: "The Frontiers of Quantum Computing."

So what started with a phone call resulted in MITRE becoming co-sponsor of and participant in the "Frontiers" program, which began in September 2007 and will continue to the end of the 2007-2008 academic year.

A Major Effort Starts Small

A single call became an ongoing partnership after Curtis Callan, the director of the Princeton Center for Theoretical Physics, asked for Gerry Gilbert's help in organizing the research agenda for the Center.

Callan, who also holds the title of James S. McDonnell Distinguished University Professor of Physics, says he was familiar with the "excellent MITRE effort in quantum information, led by Gerry, which had already established a strong collaboration on error-correcting codes in quantum computation." He was referring to Gilbert's collaboration with Callan's Princeton colleague, mathematician Robert Calderbank, former vice president of research at AT&T Labs and a coding and information theorist with an international reputation. Calderbank is both a professor of engineering and mathematics and the director of the university's Program in Applied and Computational Mathematics.

"Princeton was already well aware of our quantum computing work on campus with its researchers," remarked Gilbert about the invitation. "However, Professor Callan's call was a quite a surprise because he'd not been directly involved with our work. We were honored and, quite frankly, flattered to have been so noticed."

Going Quantum Under One Roof

The MITRE/Princeton joint research effort on quantum error correction and fault tolerance is vital to the field because if quantum information cannot be protected from errors, then it's impossible to have a fault-tolerant quantum computer. Classical computers overcome errors by way of redundancy; a quantum computer operates quite differently. (For more, see "So What Is a Quantum Computer?" below)

"Gerry has developed an approach to quantum fault tolerance that subsumes all the different perspectives advanced by the quantum information processing community," says Princeton's Robert Calderbank. The starting point is a model for quantum errors, and the objective is to build a reliable quantum computer out of unreliable components—just like we do with classical computers."

Shaping the Technical Agenda

Gilbert's keynote address at the Center's Inaugural Symposium in September touched on this as well. The paper from which he drew his talk, "A Universal Operator Theoretic Framework for Quantum Fault Tolerance"—co-written with Calderbank and his graduate student Vaneet Aggarwal, along with Gilbert's QIS Group colleagues, Michael Hamrick and Yaakov Weinstein—kicked off a year's worth of every-Wednesday symposia that bring many of the leaders in the world of quantum computation to stay in residence for a week or more of collaboration. Each Tuesday is taken up with graduate seminars; MITRE's Hamrick has already taught one.

"Gerry, Mike, and Yaakov have shaped the technical agenda of our special year in quantum information," says Calderbank, "and we have learned a great deal from their lectures." For Gilbert and his QIS mates, it's a two-way street: new perspectives, new techniques, economies in research methodology, collaboration at the highest levels, and full use of laboratory apparatus at a preeminent research university have united to benefit the quantum expertise and acquired knowledge base that MITRE can offer its sponsors. As Gilbert sees it, "It's invaluable research that the government could acquire in no other way."

MITRE, in our role as trusted technical counsel to our government sponsors, has a well-informed perspective on what in government circles is perceived as "must-have" emerging technology. "The impact of the quantum computer, if it can be done, will be really, really revolutionary," said Tony Tether, head of the Defense Advanced Research Projects Agency, in a recent interview with Wired magazine. "You can get great, great parallel processing." But he's apprehensive as well: "It is something that, if somebody else got it before us, would be a great technological surprise."

A Frontier with Lots of Promise

The year-long "Frontiers of Quantum Computing" program previews how huge the stakes are in the competition for quantum computation. Take Shor's algorithm, for instance. Running on a quantum computer it could factor in a few minutes numbers that would take millennia to factor on classical computers, including supercomputers. Because Internet banking, credit card transactions, and secret communications are protected by similar security codes that are effectively impossible to "classically" factor, it's easy to speculate about the impact of a quantum computer on the financial industry, online retailers, the military, and intelligence organizations, among others. Using quantum simulation, reported Information Week in the article "Quantum's Next Leap," a quantum computer could also "model complicated molecules in the search for new drugs by quickly solving the quantum [dynamical] equations that govern the motion of all the electrons, protons, and other components of the molecule."

"The ideas are just flying back and forth," says Calderbank of the MITRE/Princeton quantum connection. As it happens, Calderbank and Gilbert first met at an MIT meeting on quantum calculation and instantaneous radar polarimetry, or IRP. (A vital tool in sensor technology, IRP is concerned with the measurement and calculation of polarized radar waves and the scattered waves extracted from targets). "The mathematics of quantum information processing is also the mathematics that makes IRP possible," he explains. The QIS Group then invited Calderbank to MITRE to speak on the topic, and the collaboration began in earnest.

Such cross-pollination of ideas is the stuff that brings a smile to the face of Henry Bayard, MITRE's Director of Emerging & Disruptive Technology. The yoking together of ideas about quantum computation with radar is the kind of thinking that precedes the breakout of new technology. Gilbert's QIS Group, one of five such emerging technology activities under Bayard's supervision, is on "the doorstep of some important quantum breakthroughs," he says. "And Gerry's just the right guy to push us through to the other side."

So What Is a Quantum Computer?

The reality of quantum computation today is that there aren't any large-scale quantum computers with which to do computations.

That being said, the resources to perform quantum computations are at hand in a number of labs around the world. These resources center on controlling "qubits" (quantum bits), which are similar to, but in critical ways very different from, the 0 or 1 binary bits of classical computing.

The circuitry of today's microprocessors is flooded with streams of electrons switching millions of transistors on and off, creating the familiar binary bits 0 and 1. A qubit, however, is a single, two-level quantum system; a prime example being the so-called "spin" of particles such as electrons. With an individual electron or other suitable particle held in a quantum dot or nanostructure, a magnetic field can be used to change the spin state of the electron from "up" to "down", corresponding to the binary 0 and 1. But there is a difference. In the quantum world of individual electrons, photons, etc., classical physics, like that of Newton's or Maxwell's equations, does not accurately describe what's going on; rather, the domain of individual elementary particles is ruled by quantum physics. It's a quirky place where an electron spin can be a "0"or a "1" or both simultaneously.

What makes quantum bits so powerful is in the way a quantum computer uses them to perform calculations. Classical bit operations are performed serially—one at a time. For example, a one gigahertz desktop or laptop computer performs individual bit operations at a rate of one billion a second. A quantum computer, on the other hand, calculates in parallel—all at once. According to physicist David Deutsch, "a 30-qubit quantum computer would therefore equal the processing power of a classical computer running at 10 teraflops or 10 trillion computations a second." Of course, this assumes an ideal quantum computer. "The research being performed by my MITRE QIS Group," says Gilbert, "together with Princeton's Calderbank on quantum error correction and fault tolerance, is revealing how this estimate must be modified for practical implementation of quantum computing machines."

Still a work in progress, quantum computing is closing in on a time when small quantum computing machines comprised of a few qubits will appear on the research scene. At first, they'll probably come as quantum peripherals tied to classical computers, with the peripheral used only for specialized tasks. Until then, the security of current banking codes can be maintained. But with all the attention being given to quantum computing, traditional computing may soon be in store for some mighty stiff competition.

—by Tom Green

Related Information

Articles and News

Technical Papers and Presentations

Quantum Computing [PDF, 154KB]

Websites

Page last updated: February 12, 2008 | Top of page

	Solutions That Make a Difference.® Copyright © 1997-2013, The MITRE Corporation. All rights reserved. MITRE is a registered trademark of The MITRE Corporation. Material on this site may be copied and distributed with permission only.
	Privacy Policy \| Contact Us