Boson Sampling on a Photonic Chip
Justin B. Spring, Benjamin J. Metcalf, Peter C. Humphreys, W. Steven Kolthammer, Xian‐Min Jin, Marco Barbieri, Animesh Datta, Nicholas L. Thomas-Peter, Nathan K. Langford, Dmytro O. Kundys, James C. Gates, Brian J. Smith, Peter G. R. Smith, Ian A. Walmsley · Science · 2012
Computing Power of Quantum Mechanics There is much interest in developing quantum computers in order to perform certain tasks much faster than, or that are intractable for, a classical computer. A general quantum computer, however, requires the fabrication and operation a number of quantum logic devices (see the Perspective by Franson ). Broome et al. (p. 794 , published online 20 December) and Spring et al. (p. 798 , published online 20 December) describe experiments in which single photons and quantum interference were used to perform a calculation (the permanent of a matrix) that is very difficult on a classical computer. Similar to random walks, quantum walks on a graph describe the movement of a walker on a set of predetermined paths; instead of flipping a coin to decide which way to go at each point, a quantum walker can take several paths at once. Childs et al. (p. 791 ) propose an architecture for a quantum computer, based on quantum walks of multiple interacting walkers. The system is capable of performing any quantum operation using a subset of its nodes, with the size of the subset scaling favorably with the complexity of the operation.