Government researchers have spent a decade investigating computers
that use the principles of quantum mechanics to process information
much faster than currently possible. The promise of quantum computers
is enormous, but experts within the U.S. military research community
disagree on the scope and utility of this technology.
Experts point out that quantum computers could execute calculations
several millions of times faster than conventional systems, but
that the technology still is years away from becoming truly functional.
Interest in quantum computing is growing. Since 1994, the government’s
annual funding of quantum computing programs has gone from near-zero
to $80 million a year, noted Henry Everitt, chief scientist for
the Army Research Office.
Everitt manages one of the nation’s largest programs in quantum
computing. Other key players are the Defense Advanced Research Projects
Agency, the National Security Agency and the Advanced Research and
Twice a year, since 1999, Everitt has chaired a meeting with the
dozen or so federal agencies currently researching quantum computing.
“My collaborative agencies are asking if one could be built,”
Everitt said in an interview. “Frankly, I have my doubts.”
Everitt’s effort is aimed at determining if the laws of physics
would allow a quantum computer to exist. On that front, at least,
things look hopeful. “So far the physics seem to be accommodating,”
If quantum computing seems esoteric, that’s because it makes
little sense to those who aren’t particle physicists. Quantum
mechanics is the study of matter at the atomic level, where the
“normal” rules of physics don’t apply.
Traditional computers encode information in a series of bits, and
manipulate them in a specific order. They can do these manipulations
very quickly. But a quantum computer could do a lot more at the
same time, taking advantage of the oddities found at the atomic
Quantum objects can exist in multiple states simultaneously. By
taking advantage of this phenomenon, quantum computers could perform
simultaneous factoring. Bringing that theory to a workable reality,
however, is still a daunting challenge.
One problem facing scientists is the inability to keep the inner
workings of a quantum computer stable. Quantum bits are like little
tops spinning about an externally applied magnetic field at a known
frequency (for example, 500 million revolutions a second.) If the
spin rate changes even slightly, the bits’ orientation can
change and cause errors.
The premier application of a quantum computer lies in the field
of encryption. But other benefits of even a selectively deployed
quantum computer system could revolutionize the way military commanders
allocate resources and execute operations.
The problem is often called the “Traveling Salesman,”
which tries to find the shortest route between X number of cities
the vendor must visit. As the value of X increases, the problem
gets exponentially harder. Finding the best route without testing
every possible route against each other, one by one, and assessing
results, is the holy grail of information technology, Everitt said.
Peter Shor, a researcher at AT&T’s Bell Laboratories
and now at MIT, devised the first quantum computer algorithm in
The ambition for quantum computing reached a near-fever pitch with
the discovery of Grover’s Algorithm—a powerful database
search for a quantum computer that could find a needle in a haystack
by identifying every strand of hay at once, rather than looking
for the anomaly one-at-a-time. But Everitt said results have been
disappointing so far. “We don’t have an algorithm for
that,” he said. “There are whole classes of problems
quantum computing can’t be used for.”
Everitt holds workshops to investigate other possible applications
of the nascent technology. One such workshop in December was dedicated
to the potential use of quantum computers in signal and image processing.
“The answer was, ‘Eh? We don’t know.”
That is the conundrum for quantum computers; the emergence of such
a powerful tool comes with relatively few real-world applications.
“Most people would never see or use a quantum computer,”
said Everitt. “This is not one of those things which will
replace all computers.”
Others are more optimistic. Jeffrey Yepez, senior physicist at
the Air Force Research Laboratory at Hanscom Air Force Base, Mass.,
sees great potential of quantum computers to force a massive change
in information technology.
“If we are successful at nanometer scale engineering and
in turn able to construct a large quantum computer, we can safely
predict today that this…will usher in another revolution tomorrow,
which may be called the quantum revolution,” he wrote in response
to questions from National Defense.
In February 2004, Yepez wrote a memorandum to the Air Force on
the topic of potential applications of quantum computing. Among
the uses were drastic improvements in control, communications, intelligence,
surveillance and reconnaissance.
Quantum clock synchronization could change operating procedures
across the entire military, and using low-power quantum devices
on space-based platforms would help the United States maintain space
dominance via space-based quantum sensors, secure communications
and on-board data processing.
Yepez acknowledges that large amount of work is needed to achieve
Everitt said that in many ways, the Defense Department is waiting
to see whether a quantum computer will become a reality before taking
any serious steps towards fully perusing the technology. “I
wouldn’t say they’re being myopic. I’d say they’re
being cautious,” Everitt said. “They’re betting
on failure, and they may be right. We’ll see soon enough.”
One area where quantum mechanics has enormous potential in the
defense market is for secure communications. Quantum cryptography
enables parties to secure their communications by encoding a secret
key with single photons, making any attempt at eavesdropping or
code-cracking immediately discovered. The mere act of intercepting
a photon to observe, read, copy or clone it irretrievably changes
that photon. The more information that is obtained, the more photons
are disrupted, and the more obvious the intrusion.
That is the basis of a project undertaken at Los Alamos National
Laboratory. Researchers there, working with an international team,
have developed a quantum cryptography technology. They received
a $1.3 million prize from the European Union for their work on establishing
quantum communications systems that run on particles of light.
The feasibility of quantum cryptography has been demonstrated in
laboratories since the 1980s. Recent attempts use dedicated fiber-optic
lines. The technology has problems, mostly related to imperfections
of the photon sources.
There are already products on the market using quantum mechanics.
A company called MagiQ Technologies is researching quantum computers,
but also is selling quantum-based cryptography and communications
systems. Quantum cryptographic key is already for sale, using the
photon-by-photon encryption. Company officials said the initial
markets for these quantum encryption keys are government agencies
and financial institutions.
The flip side to the cryptography is code-breaking, an area where
the U.S. military could find itself on the wrong end of quantum
physics. Many U.S. government agencies employ today’s premier
encryption code, called RSA. The advent of a computer that could
crack that code would be a grave threat, officials said.
But if a quantum computer of significant size and stability were
created, Everitt said the reaction from the defense and intelligence
communities would be immediate.
Quantum computers could process algorithms that the fastest existing
supercomputer would need years to complete. That puts all codes
and communications at risk—and could fuel the next boom in
quantum computing research, Everitt said.