Barrett Alosa: The DNA computer probably has smaller technical hurdles than the quantum computer. Quantum computers have to fight decoherence which is a fundamental decay of the information in the computer. To be able to fight decoherence, the decoherence time must be long compared to the operation time. Only a handful of quantum systems have come close to that requirement, and even then, they are still no where near close enough to be useful after millions of operations. Quantum computers also use more complicated information carriers that must be operated on with very great precision. Imagine a classical computer (including DNA computers) as being a coin. A coin can either be up or down. A quantum computer is like a ball. The state of the ball is whichever part of the ball is touching the table on which it rests. There are an infinite number of states of the ball, as opposed to 2 states of the coin (up or down). To change the state of the sphere to another sta! te takes a very precise rolling operation where you need to apply it for just the perfect amount of time to rotate the ball to the intended location. To change the coin, you just flip it. The ball is much more difficult to work with. It is also much more error prone because the slightest wind will move the ball to another state, while the coin could only be affected by the most immense gale. In much the same way, quantum computers are much more difficult to work with than classical computers (including DNA computers). So I predict a useful DNA computer coming out before a useful quantum computer.You should also realize that there is a fundamental difference between quantum computers and classical computers. It is not simply that a quantum computer will be faster. A quantum computer is a different type of information manipulation. Let's make an analogy, quantum computers are to classical computers as calculus is to arithmetic. Calculus includes everything in arithmet! ic, but it introduces many things that are not part of arithme! tic so that it can solve different problems. Quantum computers are not doing the same thing as classical computers. They are doing different things. They are fundamentally different machines that work on different mathematical principles. DNA computers, on the other hand, simply do the same thing as a classical computer, just potentially faster. Quantum computers, as they do different things, will not be better at most types of problems. A quantum computer will not help you play games faster or boot faster or anything like that. They will only help you if you do one of the 3 or 4 problems that quantum computers are better at. And chances are you will not be interested in those problems (which are factoring, unstructured search, and quantum simulation). As far as do DNA and quantum computers currently exist, the answer is sort of. The DNA computer link from the other answerer shows that a simple DNA computer that is very slow has been created. Simple quantum compu! ters also exist. There are NMR-based systems that have been used to factor the number 15 (the answer is 3*5, if you are curious). There was recently a demonstration of a two-qubit quantum processor using trapped ions. This is the simplest computer that can be made and still called a computer, but it is big news because it is the first demonstration of a quantum computer using a scalable system, that in theory, could be made arbitrarily large. There is also a company called D-Wave that makes something that they call a quantum computer, but does not fit the definition of a quantum computer as defined by everyone else. So, yes, simple DNA and quantum computers exist. But none of these are useful in that they do not outperform current computer technology in any task....Show more
Emery Blando: My Grandmother was born in the Mumbles. I like the seaside so I'd choose that. I like icecream too.
Jude Colbenson: A working quantum computer has not been built yet. A ! DNA computer has been built:http://en.wikipedia.org/wiki/MAYA_II
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