Quantum Pattern Matching Fast on Average
Quantum Pattern Matching Fast on Average
复制标题
量子模式匹配平均速度快
作者:
A. Montanaro
The d-dimensional pattern matching problem is to find an occurrence of a pattern of length m×⋯×mdocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$m imes dots imes m$$end{document} within a text of length n×⋯×ndocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$n imes dots imes n$$end{document}, with n≥mdocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$n ge m$$end{document}. This task models various problems in text and image processing, among other application areas. This work describes a quantum algorithm which solves the pattern matching problem for random patterns and texts in time O~((n/m)d/22O(d3/2logm))documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$widetilde{O}((n/m)^{d/2} 2^{O(d^{3/2}sqrt{log m})})$$end{document}. For large m this is super-polynomially faster than the best possible classical algorithm, which requires time Ω~(nd/2+(n/m)d)documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$widetilde{Omega }( n^{d/2} + (n/m)^d)$$end{document}. The algorithm is based on the use of a quantum subroutine for finding hidden shifts in d dimensions, which is a variant of algorithms proposed by Kuperberg.