First-ever calculation performed on optical quantum computer chip
(麻豆淫院Org.com) -- A primitive quantum computer that uses single particles of light (photons) whizzing through a silicon chip has performed its first mathematical calculation. This is the first time a calculation has been performed on a photonic chip and it is major step forward in the quest to realise a super-powerful quantum computer.
The chip takes four photons that carry the input for the calculation, it then implements a quantum programme (Shor鈥檚 algorithm) to find the prime factors of 15, and outputs the answer - 3 and 5. The results are reported by a team of physicists and engineers from the University of Bristol in today鈥檚 issue of Science.
鈥淭his task could be done much faster by any school kid,鈥� said PhD student, Alberto Politi, who, together with fellow PhD student Jonathan Matthews performed the experiment, 鈥渂ut this is a really important proof-of-principle demonstration.鈥�
Finding prime factors may seem like a mathematical abstraction, but it lies at the heart of modern encryption schemes, including those used for secure internet communication. The ability of quantum computers to simulate quantum systems may also prove to be a powerful tool in the development of new materials or pharmaceuticals.
The team from the University of Bristol鈥檚 newly established Centre for Nanoscience and Quantum Information have spent several years developing devices where photons propagate in silica waveguides 鈥� much like in optical fibres 鈥� micro-fabricated on a silicon chip.
鈥淭his approach results in miniature, high-performance and scalable devices,鈥� said Professor Jeremy O鈥橞rien, Director of the Centre for Quantum Photonics, who led the research. 鈥淭he realisation of a quantum algorithm on a chip is an extremely important step towards an all-optical quantum computer鈥�
鈥淒espite recent advances, the ability to perform even small-scale quantum algorithms has largely been missing,鈥� said Matthews. 鈥淔or the last few years, researchers at the Centre for Quantum Photonics have been working towards building fully functional quantum circuits on a chip to solve this issue,鈥� added O鈥橞rien.
The team coupled four photons into and out of the chip using optical fibres. On the chip the photons traveled through silica waveguides that were brought together to form a sequence of quantum logic gates. The output was determined by which waveguides the photons exited the chip in. By detecting the photons at the output of the device they confirmed high-performance operation of the quantum algorithm.
鈥淎s well as quantum computing and quantum metrology, 鈥榦n-chip鈥� photonic quantum circuits could have important applications in quantum communication, since they can be easily integrated with optical fibres to send photons between remote locations,鈥� said Politi.
O鈥橞rien concurred and added: 鈥淭he really exciting thing about this result is that it will enable the development of large scale quantum circuits for photons. This opens up all kinds of possibilities鈥�.
More information: Shor鈥檚 Quantum Factoring Algorithm on a Photonic Chip by Alberto Politi, Jonathan C. F. Matthews and Jeremy L. O'Brien. Science, 4 September 2009.
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Provided by University of Bristol ( : )
