A fast quantum mechanical algorithm for database search
STOC '96 Proceedings of the twenty-eighth annual ACM symposium on Theory of computing
Strengths and Weaknesses of Quantum Computing
SIAM Journal on Computing
Simulating quantum mechanics on a quantum computer
PhysComp96 Proceedings of the fourth workshop on Physics and computation
Quantum computation and quantum information
Quantum computation and quantum information
Introduction to Algorithms
ICALP '98 Proceedings of the 25th International Colloquium on Automata, Languages and Programming
Algorithms for quantum computation: discrete logarithms and factoring
SFCS '94 Proceedings of the 35th Annual Symposium on Foundations of Computer Science
Quantum computing and communications - Introduction and challenges
Computers and Electrical Engineering
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Many information processing and computing problems can be traced back to find the extreme value of a database or a function. Unfortunately, classical solutions suffer from high computational complexity if the database is unsorted or, equivalently, the function has many local minimum/maximum points. Proposed quantum computing-based solutions involve the repeated application of Grover's searching algorithm. In this paper, we introduce a new technique exploiting the parallel processing capabilities of quantum computing in a different way. We derive a special case of quantum counting—we call it quantum existence testing— which allows adapting the classical logarithmic search algorithm so that it is suitable for structured databases to unstructured ones. The paper analyzes the required number of database queries, the corresponding computational complexity, and the probability of error and their relationship.