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Microsoft into quantum computing

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Jun 26, 2014, 12:19:47 PM6/26/14

Microsoft Makes Bet Quantum Computing Is Next Breakthrough


Michael Freedman, Sankar Das Sarma and Chetan Nayak proposed a
computing model in 2005 that can be used to construct qubits, the
foundation of quantum computing.

Emily Berl for The New York Times


June 23, 2014
SANTA BARBARA, Calif. � Modern computers are not unlike the looms of
the industrial revolution: They follow programmed instructions to
weave intricate patterns. With a loom, you see the result in a cloth
or carpet. With a computer, you see it on an electronic display.

Now a group of physicists and computer scientists funded by Microsoft
is trying to take the analogy of interwoven threads to what some
believe will be the next great leap in computing, so-called quantum

If the scientists are right, their research could lead to the design
of computers that are far more powerful than today�s supercomputers
and could solve problems in fields as diverse as chemistry, material
science, artificial intelligence and code-breaking.

They met here this weekend to explore an approach to quantum computing
that is based on �braiding� exotic particles known as anyons � what
physicists describe as �quasiparticles� that exist in just two
dimensions rather than three � in order to form the building blocks of
a supercomputer that exploits the weird physical properties of
subatomic particles.

The proposed Microsoft computer is mind-bending even by the standards
of the mostly hypothetical world of quantum computing.

Conventional computing is based on a bit that can be either a 1 or a
0, representing a single value in a computation. But quantum computing
is based on qubits, which simultaneously represent both zero and one
values. If they are placed in an �entangled� state � physically
separated but acting as though they are connected � with many other
qubits, they can represent a vast number of values simultaneously.

And the existing limitations of computing power are thrown out the

In the approach that Microsoft is pursuing, which is described as
�topological quantum computing,� precisely controlling the motions of
pairs of subatomic particles as they wind around one another would
manipulate entangled quantum bits. Although the process of braiding
particles takes place at subatomic scales, it is evocative of the
motions of a weaver overlapping threads to create a pattern.

By weaving the particles around one another, topological quantum
computers would generate imaginary threads whose knots and twists
would create a powerful computing system. Most important, the
mathematics of their motions would correct errors that have so far
proved to be the most daunting challenge facing quantum computer

First proposed by the physicist Richard Feynman in 1982, quantum
computing has mostly been of interest to academics, the National
Security Agency and the Pentagon�s Defense Advanced Research Projects

But in recent years, quantum computing has caught the attention of the
corporate world. Microsoft established a significant quantum computing
research effort in 2006, creating the Station Q research group at the
University of California, Santa Barbara. Since then, I.B.M., Northrop
Grumman and BBN Technologies have also begun quantum computing
research focused on earlier efforts to create qubits based on
measuring the spin of an electron or the polarization of a photon.

While scientists have created individual qubits, they are extremely
fragile, and creating the arrays of hundreds or thousands of circuits
necessary to build a useful quantum computer has proved daunting.

D-Wave Systems, a Canadian company that has had support from NASA,
Google and Lockheed Martin, has made claims that it has been able to
speed up some computing problems based on what it describes as �the
first commercial quantum computer.�

On Thursday, however, an independent group of scientists reported in
the journal Science that they had so far found no evidence of the kind
of speedup that is expected from a quantum computer in tests of a 503
qubit D-Wave computer. The company said through a spokesman that the
kinds of problems the scientists evaluated would not benefit from the
D-Wave design.

Microsoft�s topological approach is generally perceived as the most
high-risk by scientists, because the type of exotic anyon particle
needed to generate qubits has not been definitively proved to exist.

That may change soon. The company has been spending heavily and is
contributing to 10 of the roughly 20 academic research groups
exploring a long-hypothesized class of subatomic particles known as
Majorana fermions. Beyond being a scientific advance, proving the
existence of the Majorana would mean that it was likely they could be
used to form qubits for this new form of quantum computing.

Microsoft supported research, led by the physicist Leo Kouwenhoven at
the Kavli Institute of Nanoscience at the Delft University of
Technology in the Netherlands, that in 2012 produced the strongest
evidence that the long-predicted particles exist.

�They have really done something very special,� said Charles M.
Marcus, a physicist at the University of Copenhagen. �It�s been very
enabling of our research and that�s not a statement about dollars,
that�s a statement about community.�

His laboratory is now growing molecular-scale nano-wires that will
work like one-dimensional train tracks, making it possible to control
the movement of fermions around one another. They are hopeful that
they can engineer networks of the nano-wires to move fermions around
like trains in a railroad switching yard.

Ensembles of these particles that can be precisely controlled inside
exotic materials at extremely low temperature can be used to construct
qubits in the topological computing model proposed by the
mathematician Michael Freedman and the physicists Chetan Nayak and
Sankar Das Sarma in 2005. If this type of qubit can be confirmed, it
will have much higher resistance to errors than other kinds of qubits
that are fashioned from electrons, photons and atomic nuclei.

Microsoft began supporting the effort after Dr. Freedman, who has won
both the Fields Medal and a MacArthur Fellowship and is widely known
for his work in the mathematical field of topology, approached Craig
Mundie, one of Microsoft�s top executives, and convinced him there was
a new path to quantum computing based on ideas in topology originally
proposed in 1997 by the physicist Alexei Kitaev.

Mr. Mundie said the idea struck him as the kind of gamble the company
should be pursuing.

�It�s hard to find things that you could say, I know that�s a 20-year
problem and would be worth doing,� he said. �But this one struck me as
being in that category.�

Indeed, the researchers are quick to acknowledge that they have not
yet even made a working prototype of the basic element of their
system. But Microsoft is exploring what a prototype might look like
should efforts to build qubits succeed.

Burton Smith, a well-known supercomputer designer who came to
Microsoft from Cray in 2005 has moved to lead a new quantum hardware
design group. Last week, he hired Douglas M. Carmean, an Intel Fellow
who led the design of several of the firm�s microprocessors, to join
the effort.

For some time, many thought quantum computers were useful only for
factoring huge numbers � good for N.S.A. code breakers but few others.
But new algorithms for quantum machines have begun to emerge in areas
as varied as searching large amounts of data or modeling drugs. Now
many scientists believe that quantum computers could tackle new kinds
of problems that have yet to be defined.

Indeed, when Mr. Mundie asked Dr. Freedman what he might do with a
working quantum computer, he responded that the first thing he would
program it to do would be to model an improved version of itself.

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