Non-unitary Coupled Cluster Enabled by Mid-circuit Measurements on Quantum Computers

Fuente: arXiv
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Autori principali: Fleury, Alexandre, Brown, James, Lloyd, Erika, Hernandez, Maritza, Kim, Isaac H.
Natura: Preprint
Pubblicazione: 2024
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author Fleury, Alexandre
Brown, James
Lloyd, Erika
Hernandez, Maritza
Kim, Isaac H.
author_facet Fleury, Alexandre
Brown, James
Lloyd, Erika
Hernandez, Maritza
Kim, Isaac H.
contents Many quantum algorithms rely on a quality initial state for optimal performance. Preparing an initial state for specific applications can considerably reduce the cost of probabilistic algorithms such as the well studied quantum phase estimation (QPE). Fortunately, in the application space of quantum chemistry, generating approximate wave functions for molecular systems is well studied, and quantum computing algorithms stand to benefit from importing these classical methods directly into a quantum circuit. In this work, we propose a state preparation method based on coupled cluster (CC) theory, which is a pillar of quantum chemistry on classical computers, by incorporating mid-circuit measurements into the circuit construction. Currently, the most well studied state preparation method for quantum chemistry on quantum computers is the variational quantum eigensolver (VQE) with a unitary-CC with single- and double-electron excitation terms (UCCSD) ansatz whose operations are limited to unitary gates. We verify the accuracy of our state preparation protocol using mid-circuit measurements by performing energy evaluation and state overlap computation for a set of small chemical systems. We further demonstrate that our approach leads to a reduction of the classical computation overhead, and the number of CNOT and T gates by 28% and 57% on average when compared against the standard VQE-UCCSD protocol.
format Preprint
id arxiv_https___arxiv_org_abs_2406_11574
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-unitary Coupled Cluster Enabled by Mid-circuit Measurements on Quantum Computers
Fleury, Alexandre
Brown, James
Lloyd, Erika
Hernandez, Maritza
Kim, Isaac H.
Quantum Physics
Many quantum algorithms rely on a quality initial state for optimal performance. Preparing an initial state for specific applications can considerably reduce the cost of probabilistic algorithms such as the well studied quantum phase estimation (QPE). Fortunately, in the application space of quantum chemistry, generating approximate wave functions for molecular systems is well studied, and quantum computing algorithms stand to benefit from importing these classical methods directly into a quantum circuit. In this work, we propose a state preparation method based on coupled cluster (CC) theory, which is a pillar of quantum chemistry on classical computers, by incorporating mid-circuit measurements into the circuit construction. Currently, the most well studied state preparation method for quantum chemistry on quantum computers is the variational quantum eigensolver (VQE) with a unitary-CC with single- and double-electron excitation terms (UCCSD) ansatz whose operations are limited to unitary gates. We verify the accuracy of our state preparation protocol using mid-circuit measurements by performing energy evaluation and state overlap computation for a set of small chemical systems. We further demonstrate that our approach leads to a reduction of the classical computation overhead, and the number of CNOT and T gates by 28% and 57% on average when compared against the standard VQE-UCCSD protocol.
title Non-unitary Coupled Cluster Enabled by Mid-circuit Measurements on Quantum Computers
topic Quantum Physics
url https://arxiv.org/abs/2406.11574