Short-depth trial-wavefunctions for the variational quantum eigensolver based on the problem Hamiltonian
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.
Keywords
Cite
@article{arxiv.1908.09533,
title = {Short-depth trial-wavefunctions for the variational quantum eigensolver based on the problem Hamiltonian},
author = {Gian Salis and Nikolaj Moll},
journal= {arXiv preprint arXiv:1908.09533},
year = {2019}
}