Quantum Database Speeds Searches

A potential advantage of storing information in the quantum phase of atoms is the speed of data retrieval. Theorists proposed in 1997 that a search algorithm could locate data in an N-state system in (root of)N steps, rather than N/2 steps under classical algorithms, and, further, that a database could be designed to be searched in a single step.

Researchers at the University of Michigan in Ann Arbor confirmed the theory in an experiment that they reported in the Jan. 21 issue of Science. They used a 1.08-µm laser to create a "database" of cesium atoms by two-photon absorption. A chirped-pulse-amplified Ti:sapphire laser provided 150-fs, 785-nm pulses to "program" the atoms and to retrieve the information. A single query identified the information with 80 to 96 percent accuracy.