Publication details

Searching via walking: How to find a marked clique of a complete graph using quantum walks

Authors

BUŽEK Vladimír HILLERY Mark REITZNER Daniel

Year of publication 2010
Type Article in Periodical
Magazine / Source Physical Review A
MU Faculty or unit

Faculty of Informatics

Citation
Web http://pra.aps.org/abstract/PRA/v81/i6/e062324
Field Informatics
Keywords Quantum walks; graphs; cliques
Description We show how a quantum walk can be used to find a marked edge or a marked complete subgraph of a complete graph. We employ a version of a quantum walk, the scattering walk, which lends itself to experimental implementation. The edges are marked by adding elements to them that impart a specific phase shift to the particle as it enters or leaves the edge. If the complete graph has N vertices and the subgraph has K vertices, the particle becomes localized on the subgraph in O(N/K) steps. This leads to a quantum search that is quadratically faster than a corresponding classical search. We show how to implement the quantum walk using a quantum circuit and a quantum oracle, which allows us to specify the resources needed for a quantitative comparison of the efficiency of classical and quantum searches, the number of oracle calls.
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