Researchers have developed a penny-sized silicon chip that uses photons to run Shor's algorithm to solve a mathematical problem.
The algorithm computes the two numbers that multiply together to form a given figure, and has until now required laboratory-sized optical computers.
This kind of factoring is the basis for a wide variety of encryption schemes.
The work reported in Science, is rudimentary but could easily be scaled up to handle more complex computing.
Shor's algorithm and the factoring of large numbers has been a particular case used to illustrate the power of quantum computing.
Quantum computers exploit the counterintuitive fact that photons or trapped atoms can exist in multiple states or "superpositions" at the same time.
For certain types of calculations, that "quantum indeterminacy" gives quantum computers a significant edge.
While traditional or "classical" computers find factoring large numbers impracticably time-consuming, for example, quantum computers can in principle crack the problem with ease.
Important step
Optical computing has been treated as the future information processing by using packets of light instead of electrons as the information carrier.
But these packets, called photons has indeterminate properties that make them quantum objects - so an optical computer can also be a quantum computer.
In fact just this kind of photon-based quantum factoring has been accomplished before, but the ability to put the heart of the machine on a standard chip is promising for future applications of the idea.
Sunday, September 06, 2009
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