Robust Quantum Algorithms Computing OR with ε-Biased Oracles

Tomoya SUZUKI
Shigeru YAMASHITA
Masaki NAKANISHI
Katsumasa WATANABE

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E90-D    No.2    pp.395-402
Publication Date: 2007/02/01
Online ISSN: 1745-1361
DOI: 10.1093/ietisy/e90-d.2.395
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on Foundations of Computer Science)
Category: Quantum Computing
Keyword: 
quantum computing,  biased oracle,  phase estimation,  

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Summary: 
This paper considers the quantum query complexity of ε-biased oracles that return the correct value with probability only 1/2 + ε. In particular, we show a quantum algorithm to compute N-bit OR functions with O(/ε) queries to ε-biased oracles. This improves the known upper bound of O(2) and matches the known lower bound; we answer the conjecture raised by the paper [1] affirmatively. We also show a quantum algorithm to cope with the situation in which we have no knowledge about the value of ε. This contrasts with the corresponding classical situation, where it is almost hopeless to construct a bounded error algorithm without knowing the value of ε.


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