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Open AccessArticle
Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements
1
Quantum Technology Lab, Dipartimento di Fisica Aldo Pontremoli, Università degli Studi di Milano, I-20133 Milano, Italy
2
Algorithmiq Ltd., Kanavakatu 3C, FI-00160 Helsinki, Finland
3
HelTeq Group, QTF Centre of Excellence, Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland
4
Pico Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland
*
Author to whom correspondence should be addressed.
Entropy 2024, 26(9), 722; https://doi.org/10.3390/e26090722 (registering DOI)
Submission received: 20 June 2024
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Revised: 13 August 2024
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Accepted: 22 August 2024
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Published: 23 August 2024
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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MDPI and ACS Style
Morrone, D.; Talarico, N.W.; Cattaneo, M.; Rossi, M.A.C.
Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements. Entropy 2024, 26, 722.
https://doi.org/10.3390/e26090722
AMA Style
Morrone D, Talarico NW, Cattaneo M, Rossi MAC.
Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements. Entropy. 2024; 26(9):722.
https://doi.org/10.3390/e26090722
Chicago/Turabian Style
Morrone, Daniele, N. Walter Talarico, Marco Cattaneo, and Matteo A. C. Rossi.
2024. "Estimating Molecular Thermal Averages with the Quantum Equation of Motion and Informationally Complete Measurements" Entropy 26, no. 9: 722.
https://doi.org/10.3390/e26090722
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