TY - JOUR
T1 - Improved quantum algorithms for the ordered search problem via semidefinite programming
JF - Physical Review A
Y1 - 2007
A1 - Andrew M. Childs
A1 - Andrew J. Landahl
A1 - Pablo A. Parrilo
AB - One of the most basic computational problems is the task of finding a desired item in an ordered list of N items. While the best classical algorithm for this problem uses log_2 N queries to the list, a quantum computer can solve the problem using a constant factor fewer queries. However, the precise value of this constant is unknown. By characterizing a class of quantum query algorithms for ordered search in terms of a semidefinite program, we find new quantum algorithms for small instances of the ordered search problem. Extending these algorithms to arbitrarily large instances using recursion, we show that there is an exact quantum ordered search algorithm using 4 log_{605} N \approx 0.433 log_2 N queries, which improves upon the previously best known exact algorithm.
VL - 75
UR - http://arxiv.org/abs/quant-ph/0608161v1
CP - 3
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.75.032335
ER -