Approximation Algorithms for Complex-Valued Ising Models on Bounded Degree Graphs [article]

Ryan L. Mann, Michael J. Bremner
2018 arXiv   pre-print
We study the problem of approximating the Ising model partition function with complex parameters on bounded degree graphs. We establish a deterministic polynomial-time approximation scheme for the partition function when the interactions and external fields are absolutely bounded close to zero. Furthermore, we prove that for this class of Ising models the partition function does not vanish. Our algorithm is based on an approach due to Barvinok for approximating evaluations of a polynomial based
more » ... on the location of the complex zeros and a technique due to Patel and Regts for efficiently computing the leading coefficients of graph polynomials on bounded degree graphs. Finally, we show how our algorithm can be extended to approximate certain output probability amplitudes of quantum circuits.
arXiv:1806.11282v1 fatcat:cyuqsil4bbe2ffzcscupsis26a