<p>On <a href="http://www.qubit.org/people/david/index.php?path=Weblog">David Deutsch's blog</a>: For a long time my standard answer to the question 'how long will it
be before the first universal quantum computer is built?' was 'several
decades at least'. In fact, I have been saying this for almost exactly
two decades … and now I am pleased to report that recent theoretical
advances have caused me to conclude that we are within sight of that
goal. It may well be achieved within the next decade. The main discovery that has made the difference is <a href="http://xxx.lanl.gov/abs/quant-ph/0508218" target="_BLANK">cluster quantum computation</a>, which is a marvellous new way of structuring quantum computations which makes them far, far easier to implement physically.
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Abstract of the article on <a href="http://xxx.lanl.gov/abs/quant-ph/0508218" target="_BLANK">cluster quantum computation</a>:
We introduce an architecture for robust and scalable quantum computation
using both stationary qubits (e.g. single photon sources made out of trapped
atoms, molecules, ions, quantum dots, or defect centers in solids) and flying
qubits (e.g. photons). Our scheme solves some of the most pressing problems in
existing non-hybrid proposals, which include the difficulty of scaling
conventional stationary qubit approaches, and the lack of practical means for
storing single photons in linear optics setups. We combine elements of two
previous proposals for distributed quantum computing, namely the efficient
photon-loss tolerant build up of cluster states by Barrett and Kok [Phys. Rev.
A 71, 060310 (2005)] with the idea of Repeat-Until-Success (RUS) quantum
computing by Lim et al. [Phys. Rev. Lett. 95, 030505 (2005)]. This idea can be
used to perform eventually deterministic two-qubit logic gates on spatially
separated stationary qubits via photon pair measurements. Under non-ideal
conditions, where photon loss is a possibility, the resulting gates can still
be used to build graph states for one-way quantum computing. In this paper, we
describe the RUS method, present possible experimental realizations, and
analyse the generation of graph states.</p>