Quantum kernels for unattributed graphs using discrete-time quantum walks

Abstract

In this paper, we develop a new family of graph kernels where the graph structure is probed by means of a discrete-time quantum walk. Given a pair of graphs, we let a quantum walk evolve on each graph and compute a density matrix with each walk. With the density matrices for the pair of graphs to hand, the kernel between the graphs is defined as the negative exponential of the quantum Jensen–Shannon divergence between their density matrices. In order to cope with large graph structures, we propose to construct a sparser version of the original graphs using the simplification method introduced in Qiu and Hancock (2007). To this end, we compute the minimum spanning tree over the commute time matrix of a graph. This spanning tree representation minimizes the number of edges of the original graph while preserving most of its structural information. The kernel between two graphs is then computed on their respective minimum spanning trees. We evaluate the performance of the proposed kernels on several standard graph datasets and we demonstrate their effectiveness and efficiency.

Publication DOI: https://doi.org/10.1016/j.patrec.2016.08.019
Divisions: College of Engineering & Physical Sciences
College of Engineering & Physical Sciences > School of Informatics and Digital Engineering > Computer Science
College of Engineering & Physical Sciences > Systems analytics research institute (SARI)
PURE Output Type: Article
Published Date: 2017-02-01
Published Online Date: 2016-09-09
Accepted Date: 2016-08-19
Submitted Date: 2015-11-30
Authors: Bai, Lu
Rossi, Luca (ORCID Profile 0000-0002-6116-9761)
Cui, Lixin
Zhang, Zhihong
Ren, Peng
Bai, Xiao
Hancock, Edwin R.

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