Scientists raise quantum error threshold

 

New design allows up to a quarter of qubits to be lost.

Researchers have devised a theoretical quantum computer that could function even if one in four quantum bits (qubits) were missing.

With scientists struggling to build devices as large as three qubits, the new method could bring future applications closer by lowering the engineering requirements of a functional machine.

University of Queensland physicist Thomas Stace worked with Sean Barrett of the Imperial College London to address two quantum information issues: decoherence and loss.

The former pertained to inaccuracies in the information carried by qubits. The latter dealt with the loss of qubits themselves.

Stace explained that quantum computers that used photons - particles of light - as qubits risked losing some of these particles as they were scattered or absorbed.

Some researchers have devised methods that could tolerate the loss of one in two qubits. Other theories allowed for decoherence in one in a hundred qubits.

But none tolerated both decoherence and loss to a great degree until now. Stace said the next most tolerant method, by Queensland physicists Michael Nielsen, Christopher Dawson and Henry Hasselgrove, tolerated 0.1 percent loss and 0.01 percent decoherence.

Stace and Barrett's method, detailed in this week's Physical Review Letters, was based on the work of the University of British Columbia's Robert Raussendorf.

While traditional machines manipulated bits sequentially, using a series of logic gates, Stace and colleagues suggested that quantum computations be performed by measuring qubits initially laid out in a complex pattern.

"As you measure a quantum state, you change it," he explained, referring to the Heisenberg Uncertainty Principle in quantum mechanics.

The universal, initial state involved sets of entangled qubits in a pattern that would depend on what type of particle - electrons, ions, or photons - the qubits were.

Qubits would then be measured in an order defined by what a user wanted to achieve. Researchers already had a method to directly map these measurements to traditional logical operations, Stace said.

Only one in four measurements needed to occur, thanks to error-correcting code that used the context of remaining qubits to decipher the information in those that had been lost.

And because operations hinged predominantly on the initial, entangled state, the system had fewer points of failure than most quantum computing models, and was thereby more robust.

Stace described it as a "divide and conquer" approach that could be easily restarted if too many measurements failed.

The researchers have discussed the method's potentials with experimentalists from Yale and Sydney University.

But experiments with large scale devices were still "easily a decade" away due to engineering difficulties, since even "elementary demonstrations" required "several tens" of qubits, Stace said.

"You could do some proof of principle with 20 qubits," he mused, noting that this may be sufficient for small, simple devices that could act as signal repeaters in quantum key distribution networks.

"I wouldn't be surprised if that happens in the next three to five years," he said.

Copyright © iTnews.com.au . All rights reserved.


Scientists raise quantum error threshold
 
 
 
Top Stories
Hockey flags billion-dollar Centrelink mainframe replacement
Claims 30 year-old tech is holding Govt back.
 
Ombudsman wants to monitor warrantless metadata access
Requests ability to report publicly.
 
Frugality as a service: the Amazon story
Behind the scenes, Amazon Web Services is one lean machine.
 
 
Sign up to receive iTnews email bulletins
   FOLLOW US...

Latest VideosSee all videos »

The great data centre opportunity on Australia's doorstep
The great data centre opportunity on Australia's doorstep
Scott Noteboom, CEO of LitBit speaking at The Australian Data Centre Strategy Summit 2014 in the Gold Coast, Queensland, Australia. http://bit.ly/1qpxVfV Scott Noteboom is a data centre engineer who led builds for Apple and Yahoo in the earliest days of the cloud, and who now eyes Asia as the next big opportunity. Read more: http://www.itnews.com.au/News/372482,how-do-we-serve-three-billion-new-internet-users.aspx#ixzz2yNLmMG5C
Interview: Karl Maftoum, CIO, ACMA
Interview: Karl Maftoum, CIO, ACMA
To COTS or not to COTS? iTnews asks Karl Maftoum, CIO of the ACMA, at the CIO Strategy Summit.
Susan Sly: What is the Role of the CIO?
Susan Sly: What is the Role of the CIO?
AEMO chief information officer Susan Sly calls for more collaboration among Australia's technology leaders at the CIO Strategy Summit.
Meet the 2014 Finance CIO of the Year
Meet the 2014 Finance CIO of the Year
Credit Union Australia's David Gee awarded Finance CIO of the Year at the iTnews Benchmark Awards.
Meet the 2014 Retail CIO of the Year
Meet the 2014 Retail CIO of the Year
Damon Rees named Retail CIO of the Year at the iTnews Benchmark Awards for his work at Woolworths.
Robyn Elliott named the 2014 Utilities CIO of the Year
Robyn Elliott named the 2014 Utilities CIO of the Year
Acting Foxtel CIO David Marks accepts an iTnews Benchmark Award on behalf of Robyn Elliott.
Meet the 2014 Industrial CIO of the Year
Meet the 2014 Industrial CIO of the Year
Sanjay Mehta named Industrial CIO of the Year at the iTnews Benchmark Awards for his work at ConocoPhillips.
Meet the 2014 Healthcare CIO of the Year
Meet the 2014 Healthcare CIO of the Year
Greg Wells named Healthcare CIO of the Year at the iTnews Benchmark Awards for his work at NSW Health.
Meet the 2014 Education CIO of the Year
Meet the 2014 Education CIO of the Year
William Confalonieri named Healthcare CIO of the Year at the iTnews Benchmark Awards for his work at Deakin University.
Meet the 2014 Government CIO of the Year
Meet the 2014 Government CIO of the Year
David Johnson named Government CIO of the Year at the iTnews Benchmark Awards for his work at the Queensland Police Service.
Q and A: Coalition Broadband Policy
Q and A: Coalition Broadband Policy
Malcolm Turnbull and Tony Abbott discuss the Coalition's broadband policy with the press.
AFP scalps hacker 'leader' inside Australia's IT ranks.
AFP scalps hacker 'leader' inside Australia's IT ranks.
The Australian Federal Police have arrested a Sydney-based IT security professional for hacking a government website.
NBN Petition Delivered To Turnbull's Office
NBN Petition Delivered To Turnbull's Office
UTS CIO: IT teams of the future
UTS CIO: IT teams of the future
UTS CIO Chrissy Burns talks data.
New UTS Building: the IT within
New UTS Building: the IT within
The IT behind tomorrow's universities.
iTnews' NBN Panel
iTnews' NBN Panel
Is your enterprise NBN-ready?
Introducing iTnews Labs
Introducing iTnews Labs
See a timelapse of the iTnews labs being unboxed, set up and switched on! iTnews will produce independent testing of the latest enterprise software to hit the market after installing a purpose-built test lab in Sydney. Watch the installation of two DL380p servers, two HP StoreVirtual 4330 storage arrays and two HP ProCurve 2920 switches.
The True Cost of BYOD
The True Cost of BYOD
iTnews' Brett Winterford gives attendees of the first 'Touch Tomorrow' event in Brisbane a brief look at his research into enterprise mobility. What are the use cases and how can they be quantified? What price should you expect to pay for securing mobile access to corporate applications? What's coming around the corner?
Ghost clouds
Ghost clouds
ACMA chair Chris Chapman says there is uncertainty over whether certain classes of cloud service providers are caught by regulations.
Was the Snowden leak inevitable?
Was the Snowden leak inevitable?
Privacy experts David Vaile (UNSW Cyberspace Law and Policy Centre) and Craig Scroggie (CEO, NextDC) claim they were not surprised by the Snowden leaks about the NSA's PRISM program.
Latest Comments
Polls
Which bank is most likely to suffer an RBS-style meltdown?





   |   View results
ANZ
  20%
 
Bankwest
  9%
 
CommBank
  12%
 
National Australia Bank
  17%
 
Suncorp
  23%
 
Westpac
  19%
TOTAL VOTES: 1515

Vote