May 13, 2013
Brighter Future With Photonic Quantum Computers
University of Vienna
Harnessing the unique features of the quantum world promises a dramatic speed-up in information processing as compared to the fastest classical machines. Scientists from the Group of Philip Walther from the Faculty of Physics, University of Vienna succeeded in prototyping a new and highly resource efficient model of a quantum computer — the boson sampling computer. The results will be published in the upcoming issue of the renowned scientific journal "Nature Photonics".
The computational power of photons
The huge advantage of photons — a particular type of bosons — lies in their high mobility. The research team from the University of Vienna in collaboration with scientist from the University of Jena (Germany) has recently realized a so-called boson sampling computer that utilizes precisely this feature of photons. They inserted photons into a complex optical network where they could propagate along many different paths. "According to the laws of quantum physics, the photons seem to take all possible paths at the same time. This is known as superposition. Amazingly, one can record the outcome of the computation rather trivially: one measures how many photons exit in which output of the network," explains Philip Walther from the Faculty of Physics.
How to beat a supercomputer
A classical computer relies on an exact description of the optical network to calculate the propagation of the photons through this circuit. For a few dozen photons and an optical network with merely a hundred inputs and outputs, even today´s fastest classical supercomputer is unable to calculate the propagation of the photons. However, for a boson sampling computer this ambitious task is within reach. The researchers met the challenge and built their prototype based on a theoretical proposal by scientists at the Massachusetts Institute of Technology (USA). "It is crucial to verify the operation of a boson-sampling computer by comparing its outcome with the predictions of quantum physics. Ironically, this test can only be performed on a classical computer. Fortunately, for small enough systems classical computers are still able to accomplish this", as Max Tillmann, first author of the publication, points out. Thus, the researchers successfully showed that their realization of the boson-sampling computer works with high precision. These encouraging results may lead the way to the first outperformance of classical computers in the not-so-far future.
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