Qubit survives record 39 minutes at room temperature | Hacker News Reader

Qubit survives record 39 minutes at room temperature

cbc.ca

145 pointsparondea21 comments

This is really exciting! For those not familiar, 180s (edit: as previously published[2]) is a phenomenal amount of time at room temperature and it seems they've beaten that now too. I was just looking for this recently in another comment thread[1] too when talking about the really cool things you can do when you have access to ultra-pure silicon-28 (which has been made as a result of something that sounds quite boring–making a more accurate standard for the kg–and is now having some exciting side benefits). Direct link to paper is here[2]; I think it's open access.

I was lucky enough to see a talk by one of the authors recently and was left very impressed. Quantum computing is probably the 'sexiest' application of ultra-pure silicon-28 but there are so many others besides, including being able to use ultra-fine optical transitions to identify defect complexes within the silicon (arrangements of impurity atoms that can influence the properties of silicon-based devices). If I remember rightly, there were several defects that had been misidentified for years based on entirely reasonable Occam's-razor like reasoning that have now been correctly identified thanks to this work.

[1] http://news.ycombinator.com/item?id=6617183

[2] http://www.sciencemag.org/content/336/6086/1280.full.pdf

That's 1800s.. a factor of 10 more!

Silicon never ceases to amaze me. While much of the research in solid state physics these days is around novel materials like graphene, silicon continues to dominate solid-state applications including all conventional computer processors and most solar cells and will prove incredibly hard to unseat in these areas. Now it appears to be a leading contender for quantum computing platforms. It's an earth-abundant material with billions of research dollars poured into it to support computing, so seeing progress in silicon quantum computing means real hope for applications.

Yes, very true, but this is in part because silicon is simply understood so well now. Trust me when I say we could do just as exciting things and more besides with other materials if we just understood them half as well!

To illustrate what I mean, consider the fact that the Czochralski process [1] exists and that it means you can get huge, pure, relatively defect-free ingots of silicon (see [2]). With new materials, we're happy just to grow a few microns of the stuff, let alone something like that.

So you're right, silicon really is very incredible :) but we've reached the point now that the new innovations are in part possible by sheer momentum alone, like the billions of dollars of investment you mention. The big challenge is to develop new materials that initially (possibly for decades or more) are inferior to silicon but might ultimately unseat it. The only problem is that no one really knows what that material will be in advance. A lot of people right now are gambling on graphene, and from the amount of investment alone something interesting should come from it, but who knows if there's something else better out there just waiting for the attention it needs.

[1] http://en.wikipedia.org/wiki/Czochralski_process [2] http://en.wikipedia.org/wiki/File:Monokristalines_Silizium_f...

Not that I disagree with what you wrote, I just want to point out that silicon dioxide is probably the most important reason silicon has reached such ubiquity in electronics. No other material has a native oxide as good as SiO2, even though the semiconductors themselves have superior properties than silicon.

The interface isn't good though.

the interface is not too shabby

That process gets you elementally pure silicon, but not isotopically pure as in this paper.

Publications from the lab: http://www.sfu.ca/physics/thewaltlab/publications.html

Thats great! I need to read the paper but if that is the life time of the physical qubit then it is much larger then what is typically considered needed for using quantum error correction to make logical qubits.

Logical qubits are made up of many physical qubits, with relatively short life times, to make one logical qubits with an infinite life time. The longer life time of logical qubits makes it considerably easier to perform long calculations and store information.

If anyone knows how easily quantum error correction can be applied to this system I would be interested in finding out.

In theory, that amount of time should allow for error correction (assuming there are more qubits to work with). The critical factor for computation is this dephasing time divided by the gate operation time (how long it takes to modify the qubit) which should be on the order of at least 10^5.

Single qubit operations have been shown to be on the order of 10's of microseconds for P nuclear spins in Si. (Unfortunately behind paywall, http://www.nature.com/nature/journal/v496/n7445/full/nature1...)

This is actually super legit, published in Science. Very exciting. I'm so proud that Canada is a world leader in quantum computing research, what with Waterloo and all the millions in funding they're spending at IQC. I hope this is the first step in achieving real quantum computers.

Except this took place at SFU.

1 minute longer than the theoretical maximum period for which you can sustain an artificial wormhole

... in the Stargate Universe

Is this in fiction or fact? If fact, can you provide some reference?

It's fiction.[1] "Artificial wormholes cannot be sustained for more than 38 minutes under normal conditions."[2]

[1] Quite enjoyable fiction. My canonically chronological SG viewing order for maximum enjoyment is available at https://docs.google.com/spreadsheet/pub?key=0AkwxWLA63pAmdG5...

[2] http://stargate.wikia.com/wiki/Wormhole_physics

39 minutes? Hmm, still not good enough for long-term backup of your qubits :)

You can use Amazon Glacier with the "Almost Absolute Zero" flag for long term storage.

Doesn't the no cloning theorem mean that you cannot back up a qubit regardless of how stable it is?

For just too often claims like that could not been proved by others. Did they release sufficient information that their experiment could be approved by others?

Reply on news.ycombinator.com