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arXiv:1910.01792 · Physical Review Research

Zero-temperature phases of the two-dimensional Hubbard-Holstein model: A non-Gaussian exact diagonalization study

Yao Wang, Ilya Esterlis, Tao Shi, J. Ignacio Cirac, Eugene Demler

Published Nov 19, 2020• 49 citations
arXivHTMLPDF

Abstract

The authors develop a variational non-Gaussian diagonalization method as an solver for strongly correlated electron-electron and electron-phonon systems, and explore the phase diagram of the two-dimensional Hubbard-Holstein model.
DOI
10.1103/physrevresearch.2.043258

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Interactions between electrons and phonons play a crucial role in quantum materials. Yet, there is no universal method that would simultaneously accurately account for strong electron-phonon interactions and electronic correlations. By combining methods of the variational quantum eigensolver and the variational non-Gaussian solver, we develop a hybrid quantum-classical algorithm suitable for this type of correlated systems. This hybrid method tackles systems with arbitrarily strong electron-phonon coupling without increasing the number of required qubits and quantum gates, as compared to purely electronic models. We benchmark the new method by applying it to the paradigmatic Hubbard-Holstein model at half filling, and show that it correctly captures the competition between charge density wave and antiferromagnetic phases, quantitatively consistent with exact diagonalization.
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