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I know quantum computers are very complicated and my question is is there any way in "Principle" to create one? Are there already quantum computers being created?

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Related: physics.stackexchange.com/q/7412/2451 and links therein. –  Qmechanic Mar 5 '13 at 21:36
    
You can buy one dwavesys.com/en/products-services.html –  Martin Beckett Mar 6 '13 at 0:59
    
"May 20, 2011, D-Wave Systems is marketing a $10,000,000 Quantum Computer named "D-Wave One" with a 128-qubit (quantum bit) chipset that performs just a single task—discrete optimization." en.wikipedia.org/wiki/… –  raindrop Mar 6 '13 at 1:34
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Some people think it is possible, some people think otherwise. Such as Leonid Levin and Oded Goldreich, who just take it as obvious that quantum computing must be impossible. Part of their argument is that it's extravagant to imagine a world where describing the state of 200 particles takes more bits then there are particles in the universe.

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I don't understand - from e.g. the commments, I was under the impression that a primitive quantum computer had been realized and was for sale. How is the position of Messrs Levin and Goldreich tenable? –  innisfree Oct 30 '13 at 14:55
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It sure is possible, there are actually already some proof-of-principle experiments implementing some elementary quantum gates or quantum algorithms.

However, there still is a long way to go. Building a useful universal quantum computer requires hundreds or thousands of quantum bits at least which is, so far, a tremendous problem. Quantum systems are very fragile and lose their quantum properties easily. You can use some error correcting codes to circumvent this but these work only for very small error rates.

All in all, we face just technological problems in building a quantum computer but it is still very far from our reach. Some people even think that we will never be able to build it. In my opinion, it will definitely take more than just ten years as Jonathan Kelsey suggests in his answer.

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yes, it's theoretically possible to create quantum computers. people are working to build prototypes of such computers all around the world.

the smallest "thing to do calculations with" in such a computer is a quantum bit (or qubit). this is the equivalent to a bit in the (ordinary) computers we use today.

check out this video and the article about qubits on Wikipedia.

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Certainly! In fact there is a set of criteria which researchers are get closer to realising every day. http://www.research.ibm.com/ss_computing/ These criteria are known as the DiVincenzo criteria.

One big step is building a universal gate known as a cnot (controlled not) from which all other quantum logic gates can be derived. IBM have done this recently. http://en.wikipedia.org/wiki/Controlled_NOT_gate

It may take under 10 years to see them realised.

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They are possible because they have been built.

http://www.pbs.org/wgbh/nova/tech/quantum-computing.html

The main issue is more getting one to function at a useable scale.

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