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MITRE's Quantum Information Program Picks Up Speed December 2002
On May 31, 2002, scientists from MITRE took the world one step closer to unlocking the secret of creating practical, unbreakable code. They did this through quantum cryptography—the gold standard of secure message transmission—a method of generating and sending encryption keys using the principles of quantum mechanics, which work at the level of subatomic particles. Even the most sophisticated standard codes have encryption keys that can be broken (at least theoretically) with ultrafast computers, since their cryptographic security relies on mathematical challenges such as the presumed difficulty of factoring large numbers. In very simple terms, quantum cryptography relies on random streams of photons—essentially, light particles—to transmit encryption keys for coding messages. Sending and receiving these streams, typically over optical fibers or free space, creates a true "one-time encryption pad" for encoding and decoding messages. Interfere in any way with the stream, and the sender automatically knows that someone is trying to tamper with the code. The quantum nature of the photons also means that an intruder can't duplicate keys. The randomness of the information bits generated by the photons guarantees that the enemy cannot read any encrypted messages. Until May 31, however, quantum cryptography was painfully slow. For the government agencies and financial institutions that maintain an intense interest in super-secure messaging, this made it a nice concept, but unrealistic for actual use in many circumstances. Transmitting quantum code through free space involves complex equipment, including photon detectors, telescopes, and lasers. Thus, sending, receiving, and transcribing the code require time and money. MITRE's achievement will help make transmission less costly. "Before our experience, the state of the art was at very slow speeds," says Gerald Gilbert, director of MITRE's Quantum Information Science (QIS) group. "Our new method will really push up the throughput of data. In our successful laboratory demonstration we have achieved a throughput that is twice the highest rate previously achieved anywhere, and the intrinsic scalability of our method should allow considerably higher increases under field conditions. This is important to the government because it eventually wants to use quantum cryptography to send large quantities of data." A MITRE-Built Design
For the last several years, Gilbert's dedicated team of researchers has been working to make practical quantum cryptography a reality. The new method, called a "high-speed free-space quantum cryptography system," enables data to flow through the air faster than the previous top rate. This opens up the possibility of harnessing quantum cryptography for satellite relays. The group ran the initial experiments in the controlled environment of MITRE's quantum computing laboratory in Eatontown, New Jersey. The breakthrough experiment & which has now been repeated successfully several times—represents a special triumph for the team. "This is very exciting because the work is an effective amalgamation of theory and experiment. Our team has worked this problem from end to end—from the theoretical to the practical. We even put together the device ourselves," Gilbert says. A specialty optics firm built some of the necessary components based on MITRE designs; other components were off-the-shelf. "It's also important to note that the work is scalable there's room to do more and make transmission even faster." From the Lab to the Sky This innovative, can-do spirit is already taking the eight-member team to the next level: moving the process outdoors into turbulent air. "Turbulence" in this case does not mean hurricane-force winds, but rather everyday air movements, such as those that create the appearance of twinkling stars. The first outside testbed will be the lab's parking lot; then the group will experiment with a span of approximately 200 meters. Gilbert notes that while others have performed quantum cryptography experiments outdoors, no other organization has achieved nearly the throughput of MITRE's tests. Successful high-speed trials at 200 meters will be followed by the toughest challenge: a 10-kilometer test, initially across horizontal ground. "It turns out that almost all turbulence occurs between sea level and an altitude of about 10 kilometers," Gilbert says. "If you can get through that, you can reach nonturbulent air—such as up to a satellite." He explains, "Satellites use cryptography to keep messages secure. The keys must be 'refreshed' periodically, but the current methods of doing this are only conditionally secret. It's theoretically possible to break their codes." And in fact, other researchers have shown that it is possible to break previously uncracked codes—using quantum algorithms. "Quantum cryptography is unconditionally secret—it's unique and different. It's an amazing phenomenon. An eavesdropper can never break it," he adds. The team hopes to run the 10-kilometer, high-speed, free-space experiment in January 2003. And then? "Well, we'll see how our work proceeds after that," Gilbert says. A Big Year for QIS MITRE's QIS program is one of the few of its kind in the world. The group is now expanding its work by tackling theoretical research in quantum computing. "We're expanding our scope," Gilbert explains. "Quantum computing involves basic math research that will lead to new quantum computing algorithms. It's the science and art of using quantum mechanics to make better computers. With this technology, we could solve math problems that are too complex for classical computers to solve in a finite amount of time. We're making progress." (Ironically, high-speed quantum computers are exactly the kind that can break current conventional codes.) While much of the QIS group's work seems to spring from the realm of science fiction—unbreakable codes, hyperfast computers—Gilbert notes that theory is rapidly becoming fact. MITRE's work in QIS has many applications, drawing the attention of the government, information security specialists, and other researchers. Gilbert's doctorate is in elementary particle physics, which serves as the foundation for quantum mechanics research. He notes, however, that relying strictly on theoretical physics wouldn't have enabled the MITRE group to achieve as much as it has. "Fortunately, MITRE is well placed to contribute to this field because of the broad backgrounds of our scientists and engineers. The nature of the field is interdisciplinary; it involves physics, mathematics, engineering, and computer science." Members of the QIS team have expertise in all these areas. Gilbert credits MITRE for enabling the group to grow from one member (himself) barely six years ago, to a team that's now breaking quantum-cryptography speed records. The corporation sponsored the team's initial research and development through the MITRE Technology Program, which funds R&D work in technologies that may someday help our sponsors solve their biggest challenges. The QIS group is now beginning to receive external support from government agencies. Being a world leader in quantum cryptography and computing puts Gilbert's team in an interesting position. "In many cases, there are no other experts to turn to for guidance," he says. "We are making discoveries as we go." As a result, MITRE has become one of the experts that others rely upon. The team shares its knowledge with the public by publishing articles in the field's leading refereed journals, as well as by speaking at and helping organize key conferences. MITRE is seeking to design, build, and demonstrate the fastest working quantum cryptography system possible. "We want to make our Quantum Information Science group the most significant in the world. Our research could be a great benefit to our sponsors and to the public at large," Gilbert says. But the dream doesn't end there. As futuristic and cutting edge as quantum cryptography and computing are, Gilbert envisions even more. "Almost every week, my young son asks me, 'Dad, have you been able to teleport anything in the lab yet?' "I just tell him: 'We're working on it.'" —by Alison Stern-Dunyak Related Information Articles and News |
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