Published in Physics World, 9 Jul 2009
Single atoms have been spotted doing the quantum version of the random walk by physicists in Germany. This sighting of a “quantum walk” could help in the design of quantum search algorithms, or in the understanding of the transition from the quantum, microscopic world to the classical, macroscopic world.
The random walk is a simple concept that has been used to describe many real-world systems from stock market prices to the Brownian motion of tiny particles floating on a liquid. It is usually described as a person who dictates his movements by the toss of a coin: get heads, for example, and he moves one step to the right; get tails and he takes a step to the left. After many coin tosses, the person’s position is random, but is most likely to be close to the start point. […]
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