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arXiv · 1908.09533

Short-depth trial-wavefunctions for the variational quantum eigensolver based on the problem Hamiltonian

Gian Salis·Nikolaj Moll
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Abstract

For the variational quantum eigensolver we propose to generate trial wavefunctions from a small amount of selected Pauli terms of the problem Hamiltonian. Two different approaches, one inspired by the quantum approximate optimization algorithm and the other by imaginary-time evolution, are proposed and studied in detail. Using numerical calculations, we study the efficiency of these trial wavefunctions for finding the ground-state energy of three molecules: H2, LiH and H2O. We find that only a small number of Pauli terms are needed to reach chemical accuracy, leading to short-depth quantum circuits with a small number of variational parameters. For the LiH molecule, the quantum circuit consists of 36 two-qubit gates, 45 one-qubit gates, and four variational parameters, with a favorable scaling for larger molecules.

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Gian Salis, Nikolaj Moll. 2019-08-26. Short-depth trial-wavefunctions for the variational quantum eigensolver based on the problem Hamiltonian. https://arxiv.org/abs/1908.09533

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