paper

Quantum Inference on Bayesian Networks

arXiv:1402.7359 · doi:10.1103/PhysRevA.89.062315

Abstract

Performing exact inference on Bayesian networks is known to be #P-hard. Typically approximate inference techniques are used instead to sample from the distribution on query variables given the values of evidence variables. Classically, a single unbiased sample is obtained from a Bayesian network on variables with at most parents per node in time , depending critically on , the probability the evidence might occur in the first place. By implementing a quantum version of rejection sampling, we obtain a square-root speedup, taking time per sample. We exploit the Bayesian network's graph structure to efficiently construct a quantum state, a q-sample, representing the intended classical distribution, and also to efficiently apply amplitude amplification, the source of our speedup. Thus, our speedup is notable as it is unrelativized -- we count primitive operations and require no blackbox oracle queries.

8 pages, 3 figures. Submitted to PRX

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