Efficient state preparation for the quantum simulation of molecules in first quantization

Fuente: arXiv
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Hauptverfasser: Huggins, William J., Leimkuhler, Oskar, Stetina, Torin F., Whaley, K. Birgitta
Format: Preprint
Veröffentlicht: 2024
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author Huggins, William J.
Leimkuhler, Oskar
Stetina, Torin F.
Whaley, K. Birgitta
author_facet Huggins, William J.
Leimkuhler, Oskar
Stetina, Torin F.
Whaley, K. Birgitta
contents The quantum simulation of real molecules and materials is one of the most highly anticipated applications of quantum computing. Algorithms for simulating electronic structure using a first-quantized plane wave representation are especially promising due to their asymptotic efficiency. However, previous proposals for preparing initial states for these simulation algorithms scale poorly with the size of the basis set. We address this shortcoming by showing how to efficiently map states defined in a Gaussian type orbital basis to a plane wave basis with a scaling that is logarithmic in the number of plane waves. Our key technical result is a proof that molecular orbitals constructed from Gaussian type basis functions can be compactly represented in a plane wave basis using matrix product states. While we expect that other approaches could achieve the same logarithmic scaling with respect to basis set size, our proposed state preparation technique is also highly efficient in practice. For example, in a series of numerical experiments on small molecules, we find that our approach allows us to prepare an approximation to the Hartree-Fock state using orders of magnitude fewer non-Clifford gates than a naive approach. By resolving the issue of state preparation, our work allows for the first quantum simulation of molecular systems whose end-to-end complexity is truly sublinear in the basis set size.
format Preprint
id arxiv_https___arxiv_org_abs_2407_00249
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Efficient state preparation for the quantum simulation of molecules in first quantization
Huggins, William J.
Leimkuhler, Oskar
Stetina, Torin F.
Whaley, K. Birgitta
Quantum Physics
The quantum simulation of real molecules and materials is one of the most highly anticipated applications of quantum computing. Algorithms for simulating electronic structure using a first-quantized plane wave representation are especially promising due to their asymptotic efficiency. However, previous proposals for preparing initial states for these simulation algorithms scale poorly with the size of the basis set. We address this shortcoming by showing how to efficiently map states defined in a Gaussian type orbital basis to a plane wave basis with a scaling that is logarithmic in the number of plane waves. Our key technical result is a proof that molecular orbitals constructed from Gaussian type basis functions can be compactly represented in a plane wave basis using matrix product states. While we expect that other approaches could achieve the same logarithmic scaling with respect to basis set size, our proposed state preparation technique is also highly efficient in practice. For example, in a series of numerical experiments on small molecules, we find that our approach allows us to prepare an approximation to the Hartree-Fock state using orders of magnitude fewer non-Clifford gates than a naive approach. By resolving the issue of state preparation, our work allows for the first quantum simulation of molecular systems whose end-to-end complexity is truly sublinear in the basis set size.
title Efficient state preparation for the quantum simulation of molecules in first quantization
topic Quantum Physics
url https://arxiv.org/abs/2407.00249