Variety of Effects of Decoherence in Quantum Algorithms


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A    No.5    pp.1284-1292
Publication Date: 2009/05/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.1284
Print ISSN: 0916-8508
Type of Manuscript: Special Section INVITED PAPER (Special Section on Frontier of Quantum Computing)
decoherence,  quantum algorithms,  Grover's database search,  quantum walks,  quantum circuits,  

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Quantum computations have so far proved to be more powerful than classical computations, but quantum computers still have not been put into practical use due to several technical issues. One of the most serious problems for realizing quantum computers is decoherence that occurs inevitably since our apparatus are surrounded with environment and open systems. In this paper, we give some surveys on a variety of effects of decoherence in quantum algorithms such as Grover's database search and quantum walks, and we show how quantum algorithms work under decoherence, how sensitive they are against decoherence, and how to implement a robust quantum circuit.