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A semiconductor developed by UB engineers provides a novel way to trap, detect and manipulate electron spin.   (Source: University at Buffalo)
Semiconductor can trap, detect and manipulate electron spin at 20 kelvins

Quantum computing is still out of reach for most mainstream industries, but continuing research in the field is making the technology more accessible. A team of engineers at the University at Buffalo have developed a semiconductor that can trap, detect and manipulate the single spin of an electron.

"The task of manipulating the spin of single electrons is a hugely daunting technological challenge that has the potential, if overcome, to open up new paradigms of nanoelectronics," said Jonathan P. Bird, Ph.D., professor of electrical engineering in the UB School of Engineering and Applied Sciences and principal investigator on the project.

The research paper (PDF) detailing the advancement is featured in this week’s Physical Review Letters. "In this paper, we demonstrate a novel approach that allows us to easily trap, manipulate and detect single-electron spins, in a scheme that has the potential to be scaled up in the future into dense, integrated circuits," added Bird.

The system developed at UB steers the electrical current in a semiconductor by applying voltage to nanoscale gaps on select metallic gates that are fabricated on its surface.

"As we increase the charge on the gates, this begins to close that gap," explained Bird, "allowing fewer and fewer electrons to pass through until eventually they all stop going through. As we squeeze off the channel, just before the gap closes completely, we can detect the trapping of the last electron in the channel and its spin."

"It was recently predicted that it should be possible to use these constrictions to trap single spins," added Bird. "In this paper, we provide evidence that such trapping can, indeed, be achieved with quantum point contacts and that it may also be manipulated electrically."

While prior efforts to trap a single spin using nanoscale semiconductors were proven successful, they had to operate at extremely cold temperatures – below 1 kelvin. According to UB researchers, cooling apparatus required to lower the temperature to such levels is not easily attainable. On the other hand, the device developed at UB is capable of performing at 20 kelvins – a temperature that the researchers believe makes their technology a more viable alternative.

Other recent advancements in quantum computing include the discovery of a "hidden" order in a quantum spin liquid, paving the way for a large number of electron spins can be coupled together to yield a quantum mechanical state with no classical analog. Scientists were also able to use pulses of light to accelerate quantum computers. Most recently, scientists at the NIST have successfully transferred data from one qubit to another by means of a microfabricated aluminum cable.

Such advancements are slowly but steadily leading up to the commercialization of quantum computer technology. Canadian firm D-Wave Systems unveiled and demonstrated earlier this year its own quantum computing technology that it aims for the commercial market – though D-Wave’s claims were met with some scepticism from the scientific community.



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woah
By ziggo on 10/17/2007 6:49:13 PM , Rating: 2
This may not seem like much but the difference between 20k and 1 k is HUGE. Advanced cryoradiators are capable of achieving these temperatures. Looks like we may be outsourcing our computing... to space.




RE: woah
By KristopherKubicki (blog) on 10/17/2007 6:51:11 PM , Rating: 2
Unfortunately I think this stuff might be too delicate to get up to space unless we start thinking about a space elevator.

But it's not exactly like we're hurting for reasons to go to space! Chalk one more up!


RE: woah
By Whedonic on 10/17/2007 7:57:27 PM , Rating: 2
Maybe build some of the more delicate components out on a space station?


RE: woah
By evildorf on 10/18/2007 12:20:14 AM , Rating: 2
The devices are actually mechanically and electrically robust if packaged properly. Though it might be more efficient to just keep things here on Earth in this case. =)


RE: woah
By Goty on 10/17/2007 10:06:44 PM , Rating: 3
The problem with moving systems like these that need to be cooled to low temperatures into space is that it's incredibly hard to remove heat from a system in a vacuum.


RE: woah
By ziggo on 10/17/2007 10:46:09 PM , Rating: 2
There are many working "cryocoolers" in space currently. Cryo-radiators are passive systems that use radiative heat transfer to eject heat to deep space. (The best possible and coldest available heat sink, though some idiot may protest on the grounds of "universal warming") The actual process of cooling in space is easy to control because of the vacuum. Makes isolating your hot parts from your cold ones much more straight forward. There are also dual stage reverse Brayton cycle coolers that use electricity to generate the work input required to "pump" the heat out to a radiator at a higher temperature. (smaller radiator required to dissipate energy)


RE: woah
By theapparition on 10/18/2007 8:56:58 AM , Rating: 2
quote:
Cryo-radiators are passive systems that use radiative heat transfer to eject heat to deep space. (The best possible and coldest available heat sink....

Not in a long shot. The 3 modes of heat transfer are conduction, convection, and radiation. In a vacuum, the only mode available is radiation, as you suggested, but that is extremely inefficient compared to the other two. It can take an equivalent surface area of a football field in space to disipate the same amount of energy as a fan in air can. Realistically, there is no such thing as a "heat sink" in space because there is nothing to sink the heat too.

quote:
The actual process of cooling in space is easy to control because of the vacuum. Makes isolating your hot parts from your cold ones much more straight forward.

While technically true, you also have to deal with radiation from other sources (e.g. the Sun). Without proper forthought, the radiators will be completely overwhealmed by the suns radiation.

The rest of your comments are spot on, but it is not easier or more efficient to cool in space.


RE: woah
By ziggo on 10/18/2007 10:31:47 AM , Rating: 2
quote:
Realistically, there is no such thing as a "heat sink" in space because there is nothing to sink the heat too.


I used the term as a concept. Radiative heat transfer doesn't require something to receive the emission for it to occur. This concept only requires that the radiator receives less radiation than it emits and the idea of space having a temperature is much easier to explain than introducing everyone to the concept that radiation IS temperature, and the background radiation (left over from the big bang) amounts to 2.2k VERY closely.

quote:
While technically true, you also have to deal with radiation from other sources (e.g. the Sun). Without proper forthought, the radiators will be completely overwhealmed by the suns radiation.


They would be, without proper shielding or forethought to how it was positioned while in orbit. These problems have already been solved. Currently sustained cooling capacities are not very high, but the technology is progressing at a rapid pace. And my opinion is that, for sustained operation at very low temperatures, space is an excellent location. It is not easy to dissipate large amounts of heat, but when you are ejecting heat to 2.2k instead of 298k it makes low temperature cooling much more feasible. Provided that 1) You don't decide to use some sort of perishable cooling system such as a compressed gas, and 2) you are not trying to cool a bank of Pentium 4's to these temperatures.


RE: woah
By therealnickdanger on 10/18/2007 4:22:39 PM , Rating: 2
Quantum-computing farm on the dark side of the Moon.


Just kelvin
By loeakaodas on 10/17/2007 8:02:52 PM , Rating: 5
It's just 20 kelvin the degree isn't used.

quote:
Before the 13th CGPM, the plural forms were “degrees Kelvin” or “degrees absolute.” The 13th CGPM changed the name to simply “kelvin” (symbol K) and the plural form became “kelvins.”


http://en.wikipedia.org/wiki/Kelvin




RE: Just kelvin
By Marcus Yam on 10/18/2007 4:12:05 AM , Rating: 2
Thanks. Learn something new every day.

Except last Friday, but that's another story.


Awesome chip
By Quiksel on 10/18/2007 10:43:14 AM , Rating: 2
The caption pic reminds me of the old cache chips I used to put into my 386.

I love how good design is never out of style. ;)

I miss my 386 :(




RE: Awesome chip
By Screwballl on 10/18/2007 11:41:37 AM , Rating: 2
I have a few in my garage if you are interested? They haven't been used in at least 6-8 years.
I am getting ready to toss them to the curb for pickup in a few weeks


RE: Awesome chip
By Quiksel on 10/18/2007 12:15:07 PM , Rating: 3
To demonstrate how geek sentimental I am, I still have the motherboard from the first 386 I had, complete with processor (those old days where the chip hardly made any heat were the DAYS!) and 4MB RAM...

I hated to do it, but I did get rid of the first computer my grandma taught me on (a super-old IBM 8088 with dual 5 1/4" drives, no HDD)... I think I'll regret that the rest of my life. :( It was my boat anchor computer... I will always miss not having it around just to look at how far we've come in 20 years.

The label of that computer was "IBMitchell" (the label had whitespace on the right hand side, so we filled it in with our last name, always a good story!)... Ahh, the memories.


Only 20 degrees Kelvin?
By Scrogneugneu on 10/17/07, Rating: 0
RE: Only 20 degrees Kelvin?
By ziggo on 10/17/2007 7:48:41 PM , Rating: 2
Simply in the realm of thermo-dynamics it is a huge difference. The background temperature of space is about 2.2k. Anything that can operate above that becomes a viable option for things outside of the labratory enviroment.


RE: Only 20 degrees Kelvin?
By MrTeal on 10/17/2007 9:14:41 PM , Rating: 2
The difference between 20K and 1K is monumental. It would allow it to be cooled by liquid helium, and thus be possible for any university or large research lab to run. Getting something down to 1K is much more difficult and expensive.


RE: Only 20 degrees Kelvin?
By jtemplin on 10/18/2007 8:36:52 AM , Rating: 2
Convincing armchair scientists that they may not be as well informed as they think they are (ahem kelvin degrees), is another monumental feat...


Heisenberg Uncertainty Principle
By encryptkeeper on 10/18/2007 10:22:00 AM , Rating: 2
So does this article mean they have gotten around that? Or are they not determining the actual location of the subatomic particles?




RE: Heisenberg Uncertainty Principle
By Ringold on 10/18/2007 12:58:33 PM , Rating: 3
Electron Spins?
By Goty on 10/17/2007 10:13:47 PM , Rating: 2
This article is a little ambiguous in its use of the term "spin". "Spin", when referring to a subatomic particle is merely a word we have assigned to one of the quantum numbers that defines every particle in our universe. Particles (ans systems of particles) can have half integer or whole integer spins, and electrons are sometimes said to be "spin up" or "spin down".

When you say you are able to capture "electron spins", I'm not entirely sure what you're trying to say. Electrons HAVE spin, but the way the article states it makes it seem like an electron spin is a tangible thing.




RE: Electron Spins?
By wetwareinterface on 10/18/2007 8:52:40 AM , Rating: 2
quote:
by Goty on October 17, 2007 at 10:13 PM

This article is a little ambiguous in its use of the term "spin". "Spin", when referring to a subatomic particle is merely a word we have assigned to one of the quantum numbers that defines every particle in our universe. Particles (ans systems of particles) can have half integer or whole integer spins, and electrons are sometimes said to be "spin up" or "spin down".

When you say you are able to capture "electron spins", I'm not entirely sure what you're trying to say. Electrons HAVE spin, but the way the article states it makes it seem like an electron spin is a tangible thing.


read the artile again...

it states "As we squeeze off the channel, just before the gap closes completely, we can detect the trapping of the last electron in the channel and its spin."

aka it can see the last electron as it comes into/through the gate and determine its "spin" so they are able to determine which quantum number it is. not ambiguous at all if you read the article and not just the headline.


By Hulk on 10/18/2007 12:40:22 AM , Rating: 3
I mean if they did get this quantum computing thing working I assume they be looking at it during the tests.

Then once on the market it wouldn't be watched and act completely differently;)




1 small step
By 457R4LDR34DKN07 on 10/18/2007 12:50:28 AM , Rating: 1
This looks intresing but how will it be used? as storage or could this lead to quantum memory of a sorts?




RE: 1 small step
By Nik00117 on 10/20/2007 4:45:00 AM , Rating: 2
I'm not sure how it would be used.

However i'm guessing the days of single digit GHz are coming to a end if this c omes out. Prob skip over double digit as well.


Impressed by the pace
By Anosh on 10/17/2007 7:18:52 PM , Rating: 2
I have to admit things are advancing faster than I initially thought they would.

Judging by the nature of the technology you would think it requires long term research. I guess they started the development long ago since they've now come this far




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