Researchers use silicon to push quantum computing toward reality

New tech could let quantum machines tackle huge problems

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The field was created to explain physical phenomena, like the odd actions of subatomic particles, that classical physics fails to do. With quantum computing, it's about the possibilities.

Unlike a classic computer, which uses ones and zeroes, a quantum machine uses quantum bits, or qubits, that can be both a one and a zero. It doesn't work in an orderly or linear manner. Instead, its qubits communicate with each other and calculate all the possibilities at the same time.

If a quantum machine has 200 qubits, it's calculating at 2 to the 200th power at the same time.

In the computer science and the physics communities, there is contention over whether a quantum computer has actually been built.

D-Wave Systems Inc., a Burnaby, British Columbia-based quantum computer company, claims that it has built quantum computers, using its own quantum processor built with different metals, including niobium, a soft metal that becomes superconducting when cooled to extremely low temperatures.

One of the company's machines, the D-Wave Two, is being tested by Google and NASA.

The disagreement involves whether the D-Wave machines are performing in full quantum states and if they provide any real speedup over traditional machines.

"The type of quantum machine that D-Wave has built is not what the broader quantum community would term a quantum computer," said Dzurak, who focuses on nanoelectronics and quantum computing. "The broader research community is trying to develop a type of quantum computer in which one has greater control of the quantum bits. The D-Wave machine is designed to solve a particular class of problems, not the full class of problems that a real quantum computer could solve."

Great control over the qubits is exactly what the Australian researchers are trying to provide. Both Morello and Dzurak said their methods of creating qubits have made calculations more accurate.

"You might be calculating 3+4, and you might get 8. That's an error," explained Morello. "The number encoded on the bit is not what it was intended to be because something went wrong in the operation. If the error is rare enough, you can correct it on the run. With greater accuracy, you can start to design larger quantum computers because you have the ability to correct the errors."

Since using silicon in the qubits gives them a longer life, the machine has more time to correct any errors. The researchers have stretched the world record for the longest-lasting qubit from two seconds to 30.

"Two years ago, 50% of the time the calculation was wrong," said Dzurak. "You weren't going to go very far with that. The accuracy now has gone from 50% to 99%. This is a game changer. It goes from being impressive science to a serious manufacturing technology that can be taken forward."

Using silicon and transistors that are similar to traditional transistors, also means that the qubits should be able to be manufactured in a traditional microprocessor plant without too much modification to the process.

Copyright © 2014 IDG Communications, Inc.

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