Quantum Mechanics Helps in Searching for a Needle in a Haystack

Journal Article · Tue Jul 01 00:00:00 EDT 1997 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.79.325· OSTI ID:549697

Grover, L K ^[1]

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1. 3C-404A Bell Labs, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States)

Quantum mechanics can speed up a range of search applications over unsorted data. For example, imagine a phone directory containing N names arranged in completely random order. To find someone`s phone number with a probability of 50{percent}, any classical algorithm (whether deterministic or probabilistic) will need to access the database a minimum of 0.5N times. Quantum mechanical systems can be in a superposition of states and simultaneously examine multiple names. By properly adjusting the phases of various operations, successful computations reinforce each other while others interfere randomly. As a result, the desired phone number can be obtained in only O({radical}(N)) accesses to the database. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 549697
• Journal Information: Physical Review Letters, Vol. 79, Issue 2; Other Information: PBD: Jul 1997
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
QUANTUM MECHANICS
ALGORITHMS
RANDOMNESS
PROBABILITY
FACTORIZATION