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Quantum algorithm for solving linear equations run on a quantum computer

Date: 2013-06-10
Recently, the group led by Professor Jian-Wei Pan, Chao-Yang Lu and Nai-Le Liu reported an experimental demonstration of solving linear equation systems with a quantum computer. The work is published in Physics Review Letters on June 7th.
 
Linear equations systems are widely used in almost all areas of science and engineering (such as signal processing, economics, robot control, computer science, and physics). Take weather forecast for example. It constantly needs to solve huge linear equation systems with millions of variables. If one needs to solve a linear system of equations with up to septillion variables, it will take at least hundreds of years for a supercomputer, posing a formidable challenge.
 
In 2009, Seth Lloyd from MIT and his colleagues presented a quantum algorithm for efficiently solving linear equation systems. By taking advantage of the quantum parallelism, the algorithm promises exponential speedup. That means that it will just take roughly a few seconds in solving linear systems with septillion variables by a quantum computer with GHz clock frequency.
 
The teams succeed in solving a simple 2×2 linear equation quantum circuit, and proved the principle of this quantum algorithm. This work has been chosen as Editor’s Suggestion by Physics Review Letters, and highlighted in the Physics website (http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.230501).