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Phys. Rev. A 71, 042313 (2005) [6 pages]

Lower bound for quantum phase estimation

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Arvid J. Bessen*
Department of Computer Science, Columbia University, New York, New York 10027, USA

Received 1 December 2004; published 8 April 2005

We obtain a query lower bound for quantum algorithms solving the phase estimation problem. Our analysis generalizes existing lower-bound approaches to the case where the oracle Q is given by controlled powers Qp of Q, as it is, for example, in Shor’s order-finding algorithm. In this setting we will prove a Ω(log 1∕ϵ) lower bound for the number of applications of Qp1, Qp2,…. This bound is tight due to a matching upper bound. We obtain the lower bound using a technique based on frequency analysis.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.71.042313
DOI:
10.1103/PhysRevA.71.042313
PACS:
03.67.Lx

*Electronic address: bessen@cs.columbia.edu