One of the hazards of working in science and technology is that we tend to get caught up in our own world and forget about timelines, etc. For example, at *some* point we will see quantum computing, although most physicists say it is 10-20 years off for the so-called "gate-based approaches" to quantum computing.
Universal quantum computing using quantum gates is the technique originally envisioned by David Deutsch, Charles Bennett, and other founders of the field. It is the technique for which the famous algorithms of Shor for integer factorization in RSA Cryptography, the discrete logarithm problem used by Elliptic Curve Cryptography, and the Grover algorithm for searching unstructured lists were developed. The gate-based approach to universal quantum computing is also fragile, and relies on large scale entanglement and coherent superposition of multiparticle states. An alternative has been developed recently that shows promise for being more robust than gate based universal quantum computing, called โAdiabatic Quantum Computingโ or โQuantum Computing by Adiabatic Evolutionโ, and in many cases does not rely on the delicate nature of full scale entanglement of the entire system and multiple unitary gate transformations on small subsets of qubits in the full quantum register, but only requires local interactions.
The gate-based approach is particularly susceptible to preliminary wavefunction collapse due to the large number of gate operations on a large quantum register needed to perform a general calculation. The adiabatic approach is not gate based, and there are existing adiabatic quantum computers. While adiabatic quantum computing has been shown to be Turing Complete in the general case, there has been considerable work in the application of this technique to discrete optimization, with a focus on NP-Complete and NP-Hard applications. Needless to say, I have the NP-Complete bug, but alas it appears that these problems will remain hard on quantum computing systems, although we can get "square root speedup" compared to classic computing (i.e., considerable speedup, but not the exponential speedup probably needed for the class NP-Complete). This will radically change the world... so I bought AdiabaticComputing.com and other variants.
oh well... I suppose I can just drop them in a few years if I am wrong about adiabatic systems. Here are a couple of papers if you are interested:
Adiabatic Quantum Computation is Equivalent to Standard Quantum Computation:
http://arxiv.org/PS_cache/quant-ph/pdf/0405/0405098v2.pdf
Robustness of adiabatic quantum computation:
http://arxiv.org/PS_cache/quant-ph/pdf/0108/0108048v1.pdf
NOTE: Arxiv.org papers are renowned for broken links (should be ok for a few weeks/months). This is because the papers are revised. If the links break, just google the title of the paper.
Next to some of the incredible things going on in genetics, I believe quantum computing breakthroughs will really shake up the world... I just don't know if that shakeup will be in my lifetime. For adiabatic computing I think it will, for gate based computing I am skeptical. "you pay your money and you make your choice"
the estimated sales for 2010- 2012 are promissing 
