Published: 12 May 2013, 10:01
About 700 million transistors form today's commercially available computer processors. The need for faster and faster computing power strongly relies on the increasing number of circuits used in modern computers. However, miniaturization in the IT industrial sector already reaches its limits - smaller transistors are practically impossible to realize, which restricts their number in a computer. To further increase computer power beyond the currently doable, new concepts are required.
One of such a revolutionary approach is the quantum computing. However, the development is still in the fledging stages: First simple prototypes still require the full lab space. Together with colleagues around Prof. Philip Walther from Vienna University, Prof. Alexander Szameit and his co-worker René Heilmann from the Institute of Applied Physics at the Friedrich-Schiller-Universität Jena developed an optical glass chip with the size of only a few centimeters, with which it becomes possible to compute information using so-called entangled photons. The physicists present this optical quantum computer chip in the current issue of Nature Photonics.
In their reported experiment the physicists sent entangled photons through circuits of optical waveguides and retrieve from the measured output distribution the inner structure of the circuit. This was possible only because entangled quantum particles can be in an undefined "fuzzy" state, whereas a classical computer works only with the defined states "on" and "off" - 1 and 0. Therefore, a quantum computer can process information much faster than its classical counterpart. For the same experiment, a classical calculation would have taken an almost infinite time. In this vein, the scientists from Jena and Vienna provided unequivocal proof that one can indeed perform highly non-trivial calculations in an efficient manner using quantum light.
Tillmann et al., "Experimental Boson sampling," Nature Photon. doi:10.1038/nphoton.2013.102 (2013).
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Jun.-Prof. Dr. Alexander Szameit
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