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Quantum search for multiple items using parallel queries

Lov K. Grover·Jaikumar Radhakrishnan
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Abstract

In the quantum database search problem we are required to search for an item in a database. In this paper, we consider a generalization of this problem, where we are provided d identical copes of a database each with N items which we can query in parallel. Then, given k items, we are required to determine the locations where these items are stored. We show that any quantum algorithm for this task must perform Omega(sqrt{Nk/d min{d,k}}) parallel queries. We also design an algorithm whose performance comes within a factor O(log d) of this lower bound.

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Lov K. Grover, Jaikumar Radhakrishnan. 2004-07-27. Quantum search for multiple items using parallel queries. https://arxiv.org/abs/quant-ph/0407217

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