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Researchers use a pair of entangled photons and fiber strands to create basic quantum computer

Researcher Prem Kumar, the AT&T Professor of Information Technology in the Department of Electrical Engineering and Computer Science and the director of the Center for Photonic Communication and Computing, and his research team are now one step closer to making quantum computers a reality.

Kumar and his team have demonstrated a basic building block of a quantum computer using entangled photons generated in optical fibers. Kumar says, “Because it is done with fiber and the technology that is already globally deployed, we think that it is a significant step in harnessing the power of quantum computers.”

With the computers we use today, data is processed in bits that consist of ones and zeros, or on and off states. In quantum computing, quantum bits, also known as qubits, are used that can exist in a one or zero state as well as a third state known as a “superposition.” This superposition is where a quantum computer gets the huge performance gains over current, traditional computers. The superposition allows the qubit to be both a one and zero simultaneously allowing the computer to process more information, much faster than computers today can.

Kumar and his team used a pair of photons and have been able to entangle the pair of photons in an optical fiber using the fiber’s nonlinear response. The researchers also say that the photons remain “mysteriously” entangled no matter how far you separate the two in the transmission fibers.

In the project, Kumar and his team were able to use the photons to perform a basic quantum computer task, a controlled-NOT gate, allowing two photonic qubits to interact. Kumar said in a statement, “This device that we demonstrated in the lab is a two-qubit device — nowhere near what’s needed for a quantum computer — so what can you do with it? It’s nice to demonstrate something useful to give a boost to the field, and there are some problems at hand that can be solved right now using what we have."

DailyTech reported in October of 2007 that another team of researchers working on quantum computing had been able to devise a method of controlling the spin of single electrons.



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Hold on a second here
By murphyslabrat on 4/9/2008 1:07:46 PM , Rating: 2
Couldn't you accomplish the stated goals of quantum computing with a trinary electrical system? All I am hearing (by hearing, I mean out of what I can understand..so explanations would be helpful) is that this "superposition" state allows for faster factoring of large numbers. If you had a trinary system where the third voltage was treated as a "superposition," wouldn't it accomplish the same goal?

I kind of get that they are looking into alternative materials/systems, but do you have to do both at once?




RE: Hold on a second here
By masher2 (blog) on 4/9/2008 1:15:51 PM , Rating: 5
The difference here is that a trinary system of 64 bits can be in any of 3^64 possible states -- but only one such state at a time.

A 64-qubit quantum computer, however, can exhibit 2^64 possible states...and can be in all those states at the same time. (specifically, a linear superposition of all possible states).

A trinary system is no different than a traditional binary computer, in that it has to process each state consecutively. A quantum computer can perform operations on all states simultaneously...which makes it incredibly fast for tasks such as factoring.


RE: Hold on a second here
By murphyslabrat on 4/9/2008 1:26:00 PM , Rating: 2
There we go. In almost every article I have read about it, they're always describing it like a trinary system. Thanks for the clarification.


RE: Hold on a second here
By TETRONG on 4/9/08, Rating: -1
RE: Hold on a second here
By masher2 (blog) on 4/9/2008 2:55:13 PM , Rating: 2
> "Trinary? Ternary ..."

Both are correct, though ternary admittedly has become the more favored term in the past decade or two.

> "This all smacks of 50's blind optimism about our wonderful flying cars with backseats "

A lot of those predictions from the 1950s did come true. In fact, those in regards to computers were far exceeded...no one in 1958 would have ever expected the average person to be walking around with a mainframe computer in their hip pcoket just 50 years later.

> "Where are the articles about all of the corporations who are stifling, even outright blocking any of these advances from ever seeing the light of day? How long ago did Japan have 3G again"

I know reality isn't as exciting as a conspiracy theory, but the fact is Verizon and AT&T both are trying to roll out 3G as fast as they can, without going bankrupt in the process. It's not their fault the US has a far lower population density, and US consumers are less interested in mobile internet connectivity than the Japanese (and thus less interested in paying for it).


RE: Hold on a second here
By Spuke on 4/9/2008 5:37:34 PM , Rating: 2
quote:
t's not their fault the US has a far lower population density, and US consumers are less interested in mobile internet connectivity than the Japanese
You can put me in that group. I could care less about having it on my phone.


RE: Hold on a second here
By TETRONG on 4/9/2008 8:43:41 PM , Rating: 2
Yes, I see what you mean.

Dense population=3G

Oh wait-what's this? http://arstechnica.com/journals/apple.ars/2008/04/...
Australia?


RE: Hold on a second here
By masher2 (blog) on 4/9/2008 10:14:40 PM , Rating: 2
> "Oh wait-what's this? Australia?"

Australia had very limited 3G coverage until the 2005/06 timeframe. The US has the same now...3G is limited mostly to major metropolitan areas.

So yes, Australia is about 2 years ahead in implementation. But invoking conspiracy theories to explain that discrepancy is groundless. After the Australian auction for 3G bandwidth, the government invested rather heavily in joint projects...meaning the Australian taxpayer helped foot the bill whether or not they wanted to.

The US also auctioned 3G bandwidth...but the telecomm crash meant most of the bidders went bankrupt and/or defaulted on their payments, forcing the auction to be redone. After that, you can hardly blame the new winners from moving a little slower and more cautiously on implementation.


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