Quantum leap

[R.A. Hettinga]

<http://www.canada.com/components/printstory/printstory4.aspx?id=deca9b6c-4f85-4475-87eb-1d2277bffaa0>
 

Quantum leap
A chance encounter between a computer-science professor and a physicist
launches new field of quantum cryptography

 

ALISON MACGREGOR

The Gazette

Friday, February 11, 2005


CREDIT: MARIE-FRANCE COALLIER, THE GAZETTE

Universite de Montreal's Gilles Brassard has made Canada a world leader in
the fast-growing quantum cryptography field.


It began 25 years ago in the warm coastal waters of Puerto Rico when a
stranger swam over to Gilles Brassard and struck up a conversation about
using quantum physics to make bank notes impossible to counterfeit.

"I had no idea who he was," recalled Brassard, then a 24-year-old prodigy
and computer-science professor at the Universite de Montreal. "He just
started talking nonsense about quantum physics."

The stranger turned out to be U.S. physicist Charles H. Bennett. Their
chance meeting while attending a theoretical computer science conference
would end up revolutionizing the art of code making, also known as
cryptography.

Together, Brassard and Bennett would go on to found a field of science -
quantum information processing - whose effects on society some say could
even rival the impact that the steam engine had in its time.

Already, experts agree, Brassard and Bennett's most famous invention, a
technique known as quantum cryptography, is set to eliminate terrifying
vulnerabilities that could soon arise in the way governments, banks, the
military, business and the public use computers and the Internet to
communicate and store data.

Some observers see the technology as one day making the Internet secure
enough that medical professionals could share confidential health data
online in ways that would be insecure now.

Yet for all its promise, this invention is also making governments nervous.

The ability to send unbreakable coded messages could just as easily be
exploited, authorities fear, by criminals and terrorists who now lack a
foolproof way of avoiding having their messages cracked.

In the midst of all this excitement and controversy is Montreal-based
Brassard, who has made Canada a world leader in his fast-growing field.

Because of him, Canada "has turned out to be the best place in the world"
to do research in quantum information processing, says physicist Raymond
Laflamme, a leading figure in the field who recently returned to Canada
from a post with the U.S. Department of Energy's Los Alamos National
Laboratory.

"All of this is thanks to Gilles," he says.

Barry Sanders, a quantum physicist who recently returned to Canada from a
research post in Australia, agrees, saying Brassard has played a key role
in making this country "the world leader in this field."

Brassard and Bennett's invention sprung from their discovery of how
principles from the previously unlinked fields of quantum physics and
computer science could be combined to establish an unbreakable secret key.

Instead of transmitting information along cables via electronic signals,
they use polarized photons - tiny particles of light - that are so
sensitive that when intercepted, they immediately become corrupted. This
renders the message unintelligible and tips off both sender and intended
recipient to the spying attempt.

What's causing particular excitement now is that the way that applications
of Brassard and Bennett's technology have just been commercialized and put
to market.

Since late 2003, consumers have been able to acquire quantum cryptographic
systems that make short-haul computer links unbreakable to spies. The
systems are being sold by two competitors in Geneva and New York for as
little as $70,000 U.S. Both firms' devices use Brassard and Bennett's
seminal insight.

But that's only a start, Laflamme says. "The potential is absolutely enormous."

- - -

Intrigued during their chance encounter off the shores of Puerto Rico by
the idea of impossible-to-forge bank notes, the two men repaired to
air-conditioned restaurants and cafes where they tossed it around some more.

They left the island firm friends, returning, respectively, to Montreal and
Croton-on-Hudson, a village just north of New York City, where they
continued their brainstorming.

While the anti-counterfeiting idea ultimately proved impractical, both
scientists soon realized that one of its underlying principles - a theory
that exploited the unique properties of photons - could be applied more
broadly to code making.

Cryptography has always been a race between code-makers and code-breakers.

Today's most sophisticated codes, used for the protection of information on
computers, rely on hugely complex mathematical calculations that
present-day computers aren't believed to be powerful enough to solve.

Yet as Brassard explains, it's possible someone has already figured out how
to crack these codes. If so, such a person might want to keep this quiet so
as to benefit personally, Brassard remarked, although there could also be
an altruistic reason for doing so.

The reason?

"Society would collapse, electronic commerce would collapse," Brassard
says. "There would be chaos. I would keep quiet - just as I would if I
found a new weapon of mass destruction."

But the biggest fear in the cryptographic world is that a new kind of
super-powerful "quantum computer" could soon be constructed that would have
the capacity to quickly solve the kinds of code-breaking problems that
today's computers are stumped by.

Already, experts say, a U.S. mathematician, Peter Shor, has developed a
formula that could be used by a quantum computer, once one has been built,
to crack current encryption technology.

The prospect of such a computer being constructed obviously worries
governments, business and the military - and should be of concern to all
who value their privacy.

It would be "a nuclear bomb to the Internet," says Barry Sanders, director
of the University of Calgary's Institute for Quantum Information Science.
"All of the security that we rely on when we use the Internet would be
obsolete."

And this is why Brassard and Bennett's invention is causing such a stir:
theirs is the first practical form of cryptography that could not be
broken, even by some yet-to-be-built quantum computer.

The key to the security of a quantum cryptography code, Laflamme explains,
is that it "does not involve solving a mathematical problem; it would
involve breaking the laws of physics."

Brassard and Bennett's collaboration has led to another breakthrough, too.
In an invention reminiscent of Star Trek, the two physicists and their
colleagues have developed a "quantum teleportation" technology that can
dissemble a particle of matter in one location and beam it for reassembly
in another.

This technique was invented in 1992, first tested experimentally four years
later with photons and is still being tested by scientists around the world.

(One of the co-inventers of the technique was Brassard's former student
Claude Crepeau, who now directs his own research team in quantum
information processing at McGill University.)

In 1999, the invention inspired a best-selling novel - Timeline, by Michael
Crichton - and a spinoff Hollywood movie of the same name.

Filmed in Montreal and released two years ago, the storyline features
protagonists being quantum-teleported back to the Middle Ages.

- - -

Brassard and Bennett's inventions have also generated enormous attention
from the world science media. An October 1992 cover story in Scientific
American magazine gave the duo's quantum cryptography technique its first
burst of stardom.

Now, a second wave of coverage has come as experiments prove the commercial
viability of their cryptography technique and fledgling new products make
their way to market.

Most recently, Brassard and Bennett's cryptography technique was again the
subject of a cover story - this time in the January issue of Scientific
American. They've also drawn coverage from Britain's New Scientist and as
well as in German, Australian and Japanese media outlets, among others.

Yet the technology still faces serious distance limitations. Photons can
only travel so far before they fade. They require amplification at regular
intervals if they're to be transmitted over long distances - something that
has not yet proved feasible. Scientists are working hard to overcome this
limitation.

So far, the record for transmitting coded messages through fibre-optic
cables is 100 kilometres; the maximum distance reached to date through the
air is 23 kilometres between two mountaintops.

This latter achievement is of particular significance because it's
generally considered harder to transmit photons through the thicker air
found near the Earth's surface than up toward space, where there's less
atmospheric interference.

That's why scientists are hopeful they'll soon be able to send photons to
satellites, which typically orbit 150 kilometres above the Earth. Such a
development would set the stage for the launch of the world's first truly
global unbreakable encrypted communications system.

So promising is the field of quantum information processing that
governments and corporations around the world are investing millions of
dollars in research in the field.

The first-ever local quantum-encrypted network of computers is now up and
running in Cambridge, Mass., where it is managed by the pioneering Internet
firm BBN Technologies Inc.

And the Los Alamos National Laboratory's quantum cryptography team has
joined with six European research institutions to push the field further.
In December, the team tied with another group to snag one of the world's
most prestigious science prizes - the European Union's $1.3-million (U.S.)
Descartes research prize - for its project to build a secure global quantum
cryptographic communications system.

In Canada, Research in Motion founder and co-chief executive Mike Lazaridis
put up $100 million of his own money in 1999 to fund the non-profit and
independent Perimeter Institute of Theoretical Physics in Waterloo, now a
leading centre of quantum information research. (Two more RIM executives
have since contributed another $20 million, while Ottawa and Ontario have
kicked in another $54 million.)

Last month, the University of Calgary got into the act, launching its
Institute for Quantum Information Science.

There have been commercial developments, too.

In 2003, a Swiss firm, id Quantique SA of Geneva, became the first to sell
a quantum cryptography system to the public. Another company, New York
City's MagiQ Technologies Inc., soon followed.

Yet Brassard and Bennett haven't made a penny from these ventures; they've
chosen not to patent their discovery in the hopes of fostering an
environment where colleagues can feel unhindered in their efforts to
develop the field.

Other companies with projects in the works include IBM - where Bennett is a
research fellow at the company's Yorktown Heights, N.Y., research centre -
and Japanese computing giants NEC, Fujitsu and Toshiba.

So great is the interest among potential buyers that industry analyst
Martin Illsley predicts the technology will be widespread in business and
government settings in as little as five years.

Early adopters will likely be financial institutions, governments and
telecommunications firms, said Illsley, an associate partner at consulting
firm Accenture Inc., in a telephone interview from France.

Others share that optimism. In a report, International Data Corp. has
predicted the market for quantum cryptography products will be about $30
million U.S. within three years - and about $300 million within 10 years.

- - -

Brassard has gathered a devoted group of researchers and students at the
Universite de Montreal's computer science department.

Now 49, he grew up in Ahuntsic, where his father was an accountant and his
mother taught yoga.

He credits his three older brothers - all scientists as well - with
inspiring him to pursue his precocious interest in math, a precursor to his
fascination with computers and physics.

A brilliant student, Brassard had entered secondary school by age 10 and
was already doing his undergraduate studies at the Universite de Montreal
by age 13.

At the time, he recalls, he thought there was "nothing unusual" about
attending university so young. He said other students treated him well
"even though I looked rather small and young for my age."

Now living in Outremont with his two daughters, Brassard says he reads,
cooks and listens to classical music in his spare time.

He used to play squash and go cross-country skiing too. But these days, he
says wistfully, there's no time for that. All the attention swirling about
him - and the fast pace of developments in his field - keeps Gilles
Brassard a very busy man.

amacgregor at thegazette.canwest.com

Further Readings

Bennett, C. H., Brassard, G. and Ekert, A. K., Quantum cryptography,
Scientific American, October 1992, pp. 50-57.

Stix, G., Best-Kept Secrets, Scientific American, January 2005, pp. 78-83.

Singh, S., The Code Book: The Science of Secrecy from Ancient Egypt to
Quantum Cryptography, Random House Inc., 1999.

Web Sites

Gilles Brassard: http://www.iro.umontreal.ca/~brassard

Charles Bennett: http://www.research.ibm.com/people/b/bennetc/home.html

Claude Crepeau: http://www.cs.mcgill.ca/~crepeau/

Raymond Laflamme: http://www.iqc.ca/people/rlaflamme/

Barry Sanders: http://qis.ucalgary.ca/~bsanders/Institutions

Universite de Montreal: Laboratoire d'Informatique Theorique et Quantique -
http://www.iro.umontreal.ca/labs/theorique/

McGill University: Crypto and Quantum info lab - http://crypto.cs.mcgill.ca/

Perimeter Institute of Theoretical Physics: http://www.iqc.ca/

University of Calgary's Institute for Quantum Information Science:
http://www.iqis.org/Commercial products

id Quantique SA: http://www.idquantique.com/

MagiQ Technologies Inc.: http://www.magiqtech.com/

-- 
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R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'