Two-local qubit Hamiltonians: when are they stoquastic?

Journal article (2019)

Authors

J.D. Klassen QCD/Terhal Group - QuTech Advanced Research Centre
B.M. Terhal QCD/Terhal Group - QuTech Advanced Research Centre ,
Copyright: © 2019 J.D. Klassen, B.M. Terhal
DOI: https://doi.org/10.22331/q-2019-05-06-139
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Published Date

06-05-2019

Language

English

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Abstract

We examine the problem of determining if a 2-local Hamiltonian is stoquastic by local basis changes. We analyze this problem for two-qubit Hamiltonians, presenting some basic tools and giving a concrete example where using unitaries beyond Clifford rotations is required in order to decide stoquasticity. We report on simple results for n-qubit Hamiltonians with identical 2-local terms on bipartite graphs. Our most significant result is that we give an efficient algorithm to determine whether an arbitrary n-qubit XYZ Heisenberg Hamiltonian is stoquastic by local basis changes.