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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.


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