Quantum Information Processing

, Volume 12, Issue 10, pp 3265–3274 | Cite as

An efficient quantum search engine on unsorted database



We consider the problem of finding one or more desired items out of an unsorted database. Patel has shown that if the database permits quantum queries, then mere digitization is sufficient for efficient search for one desired item. The algorithm, called factorized quantum search algorithm, presented by him can locate the desired item in an unsorted database using O(\(log_4N\)) queries to factorized oracles. But the algorithm requires that all the attribute values must be distinct from each other. In this paper, we discuss how to make a database satisfy the requirements, and present a quantum search engine based on the algorithm. Our goal is achieved by introducing auxiliary files for the attribute values that are not distinct, and converting every complex query request into a sequence of calls to factorized quantum search algorithm. The query complexity of our algorithm is O(\(log_4N\)) for most cases.


Quantum search model Quantum computation Database search Quantum search algorithm 


  1. 1.
    Grover, L.K.: Quantum mechanics helps in searching for a needle in a haystack. Phys. Rev. Lett. 79, 325–328 (1997)Google Scholar
  2. 2.
    Childs, A.M., Landahl, A.J., Parrilo, P.A.: Quantum algorithms for the ordered search problem via semidefinite programming. Phys. Rev. A 75, 032335 (2007)ADSCrossRefGoogle Scholar
  3. 3.
    Patel, A.: Quantum database search can do without sorting. Phys. Rev. A 64, 034303 (2001)ADSCrossRefGoogle Scholar
  4. 4.
    Nielson, M.A., Chuang, I.L.: Quantum Computation and Quantum Information. Cambridge University Press, Cambridge (2000)Google Scholar
  5. 5.
    Giovannetti, V., Lloyd, S., Maccone, L.: Quantum random access memory. Phys. Rev. Lett. 100, 160501 (2008)MathSciNetADSCrossRefGoogle Scholar
  6. 6.
    Elmasri, R.R., Navathe, S.B.: Fundamentals of Database System. Addison Wesley, Boston (2006)Google Scholar
  7. 7.
    Jin, W.L., Chen, X.D.: A desired state can not be found with certainty for Grover’s algorithm in a possible three-dimensional complex subspace. Quantum Inf. Process. 10, 419–429 (2011)MathSciNetCrossRefMATHGoogle Scholar
  8. 8.
    Jin, W.L.: Quantum search in a possible three-dimensional complex subspace. Quantum Inf. Process. 11, 41–54 (2012)MathSciNetADSCrossRefMATHGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.School of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhanChina
  2. 2.School of Computer ScienceLiaocheng UniversityLiaochengChina

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