BBC News, Alex
Mansfield, BBC Radio Science Unit, 16 May 2013
 |
| The machine does not fit the conventional concept of a quantum computer, but makes use of quantum effects |
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Stories
A $15m
computer that uses "quantum physics" effects to boost its speed is to
be installed at a Nasa facility.
It will be
shared by Google, Nasa, and other scientists, providing access to a machine
said to be up to 3,600 times faster than conventional computers.
Unlike
standard machines, the D-Wave Two processor appears to make use of an effect
called quantum tunnelling.
This allows
it to reach solutions to certain types of mathematical problems in fractions of
a second.
 |
| Is quantum computing possible? |
Google
wants to use the facility at Nasa's Ames Research Center in California to find
out how quantum computing might advance techniques of machine learning and
artificial intelligence, including voice recognition.
University
researchers will also get 20% of the time on the machine via the Universities
Space Research Agency (USRA).
Nasa will
likely use the commercially available machine for scheduling problems and
planning.
Canadian
company D-Wave Systems, which makes the machine, has drawn scepticism over the
years from quantum computing experts around the world.
Until
research outlined earlier this year, some even suggested its machines showed no
evidence of using specifically quantum effects.
Quantum
computing is based around exploiting the strange behaviour of matter at quantum
scales.
Most work
on this type of computing has focused on building quantum logic gates similar
to the gate devices at the basis of conventional computing.
But
physicists have repeatedly found that the problem with a gate-based approach is
keeping the quantum bits, or qubits (the basic units of quantum information),
in their quantum state.
"You
get drop out… decoherence, where the qubits lapse into being simple 1s and 0s
instead of the entangled quantum states you need. Errors creep in," says
Prof Alan Woodward of Surrey University.
One gate
opens...
Instead,
D-Wave Systems has been focused on building machines that exploit a technique
called quantum annealing - a way of distilling the optimal mathematical
solutions from all the possibilities.
 |
| Geordie Rose believes others have taken the wrong approach to quantum computing |
"The
gate model... is the single worst thing that ever happened to quantum
computing", Geordie Rose, chief technology officer for D-Wave, told BBC
Radio 4's Material World programme.
"And
when we look back 20 years from now, at the history of this field, we'll wonder
why anyone ever thought that was a good idea."
Dr Rose's
approach entails a completely different way of posing your question, and it
only works for certain questions.
But
according to a paper presented this week (the result of benchmarking tests
required by Nasa and Google), it is very fast indeed at finding the optimal
solution to a problem that potentially has many different combinations of
answers.
In one case
it took less than half a second to do something that took conventional software
30 minutes.
A classic
example of one of these "combinatorial optimisation" problems is that
of the travelling sales rep, who needs to visit several cities in one day, and
wants to know the shortest path that connects them all together in order to
minimise their mileage.
The D-Wave
Two chip can compare all the possible itineraries at once, rather than having
to work through each in turn.
Reportedly
costing up to $15m, housed in a garden shed-sized box that cools the chip to
near absolute zero, it should be installed at Nasa and available for research
by autumn 2013.
US giant
Lockheed Martin earlier this year upgraded its own D-Wave machine to the 512
qubit D-Wave Two.
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