Log Live the Qbit!

[J.A. Terranson]

http://www.theregister.co.uk/2012/07/04/quantum_computing_room_temperature/
Boffins pull off room-temp quantum computing with home-grown gems
Diamond test gives hope to luke-warm server strokers

By Brid-Aine Parnell . Get more from this author

Posted in Physics, 4th July 2012 15:02 GMT

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One of the very many reasons there won't be quantum computing any time 
soon is that the quantum bits (qubits) need to be at absolute zero - not 
very practical for the average server room, much less the lowly desktop.

However, Harvard tech boffins have come up with a way to create a qubit in 
a solid-state system at room temperature that can store information for 
nearly two seconds, an increase of around six orders of magnitude over the 
lifespan of earlier systems.

Problem solved. Except for one tiny issue: to do it, the researchers had 
to use diamonds. (The gems were lab-grown, so they didn't have to use the 
world's finite supply of naturally occurring diamonds . but still, 
building a computer out of diamonds is surely not going to be easy, is 
it?)

"We have a qubit at room temperature that we can measure with very high 
efficiency and fidelity. We can encode data in it, and we can store it for 
a relatively long time," professor of physics Mikhail Lukin (pictured on 
the left) said in a canned statement.

Scientists figured out a couple of years ago that atomic-scale impurities 
in lab-grown diamonds called nitrogen-vacancy (NV) centres behave like 
single atoms, having a spin that can be polarised. With the help of 
lasers, they can control that spin and figure out its orientation. But it 
wasn't yet an idea they tried out with qubits because they can only hold 
data for around a millionth of a second before their quantum properties 
drop out.

The Harvard boffins figured out that the NV centres would mirror carbon-13 
atoms, which are also in the diamonds. So they could put the info in a 
carbon-13 atom and monitor the NV centre to "read" the data. Whenever they 
don't want the NV centre to read the atom, they use massive amounts of 
laser light to keep it occupied.

They can also hit the diamond with radio frequency pulses to suppress 
interaction between the carbon-13 isotope and other atoms in order to 
extend the life of the qubit.

"We believe this work is limited only by technical issues, so it looks 
feasible to increase the life span into the range of hours. At that point, 
a host of real-world applications become possible," Lukin said.

The boffins foresee the system being used for paying for stuff (not the 
diamond bit, the computer bit); in highly secure networks . where it would 
be used for transmitting data; and for building quantum computers, natch.

The study was published in Science. .

//Alif

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