Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2024-09
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Mcode
Degree programme
Language
en
Pages
11
Series
Entropy, Volume 26, issue 9, pp. 1-11
Abstract
By leveraging the Variational Quantum Eigensolver (VQE), the “quantum equation of motion” (qEOM) method established itself as a promising tool for quantum chemistry on near-term quantum computers and has been used extensively to estimate molecular excited states. Here, we explore a novel application of this method, employing it to compute thermal averages of quantum systems, specifically molecules like ethylene and butadiene. A drawback of qEOM is that it requires measuring the expectation values of a large number of observables on the ground state of the system, and the number of necessary measurements can become a bottleneck of the method. In this work, we focus on measurements through informationally complete positive operator-valued measures (IC-POVMs) to achieve a reduction in the measurement overheads by estimating different observables of interest through the measurement of a single set of POVMs. We show with numerical simulations that the qEOM combined with IC-POVM measurements ensures satisfactory accuracy in the reconstruction of the thermal state with a reasonable number of shots.
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Publisher Copyright: © 2024 by the authors.
Keywords
molecular excited states, quantum algorithms, thermal states preparation
Other note
Citation
Morrone, D, Talarico, N W, Cattaneo, M & Rossi, M A C 2024, ' Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements ', Entropy, vol. 26, no. 9, 722, pp. 1-11 . https://doi.org/10.3390/e26090722