Applications of quantum simulation algorithms to obtain electronic energies of molecules on noisy intermediate-scale quantum (NISQ) devices require careful consideration of resources describing the complex electron correlation effects. In modeling second-quantized problems, the biggest challenge confronted is that the number of qubits scales linearly with the size of the molecular basis. This poses a significant limitation on the size of the basis sets and the number of correlated electrons included in quantum simulations of chemical processes. To address this issue and enable more realistic simulations on NISQ computers, we employ the double unitary coupled-cluster (DUCC) method to effectively downfold correlation effects into the reduced-size orbital space, commonly referred to as the active space. Using downfolding techniques, we demonstrate that properly constructed effective Hamiltonians can capture the effect of the whole orbital space in small-size active spaces. Combining the downfolding preprocessing technique with the variational quantum eigensolver, we solve for the ground-state energy of H2, Li2, and BeH2 in the cc-pVTZ basis using the DUCC-reduced active spaces. Finally, we compare these results to full configuration-interaction and high-level coupled-cluster reference calculations.
Metcalf, Mekena, et al. "Resource-Efficient Chemistry on Quantum Computers with the Variational Quantum Eigensolver and the Double Unitary Coupled-Cluster Approach." Journal of Chemical Theory and Computation, vol. 16, no. 10, Sep. 2020. https://doi.org/10.1021/acs.jctc.0c00421
Metcalf, Mekena, Bauman, Nicholas P., Kowalski, Karol, & de Jong, Wibe A. (2020). Resource-Efficient Chemistry on Quantum Computers with the Variational Quantum Eigensolver and the Double Unitary Coupled-Cluster Approach. Journal of Chemical Theory and Computation, 16(10). https://doi.org/10.1021/acs.jctc.0c00421
Metcalf, Mekena, Bauman, Nicholas P., Kowalski, Karol, et al., "Resource-Efficient Chemistry on Quantum Computers with the Variational Quantum Eigensolver and the Double Unitary Coupled-Cluster Approach," Journal of Chemical Theory and Computation 16, no. 10 (2020), https://doi.org/10.1021/acs.jctc.0c00421
@article{osti_1616985,
author = {Metcalf, Mekena and Bauman, Nicholas P. and Kowalski, Karol and de Jong, Wibe A.},
title = {Resource-Efficient Chemistry on Quantum Computers with the Variational Quantum Eigensolver and the Double Unitary Coupled-Cluster Approach},
annote = {Applications of quantum simulation algorithms to obtain electronic energies of molecules on noisy intermediate-scale quantum (NISQ) devices require careful consideration of resources describing the complex electron correlation effects. In modeling second-quantized problems, the biggest challenge confronted is that the number of qubits scales linearly with the size of the molecular basis. This poses a significant limitation on the size of the basis sets and the number of correlated electrons included in quantum simulations of chemical processes. To address this issue and enable more realistic simulations on NISQ computers, we employ the double unitary coupled-cluster (DUCC) method to effectively downfold correlation effects into the reduced-size orbital space, commonly referred to as the active space. Using downfolding techniques, we demonstrate that properly constructed effective Hamiltonians can capture the effect of the whole orbital space in small-size active spaces. Combining the downfolding preprocessing technique with the variational quantum eigensolver, we solve for the ground-state energy of H2, Li2, and BeH2 in the cc-pVTZ basis using the DUCC-reduced active spaces. Finally, we compare these results to full configuration-interaction and high-level coupled-cluster reference calculations.},
doi = {10.1021/acs.jctc.0c00421},
url = {https://www.osti.gov/biblio/1616985},
journal = {Journal of Chemical Theory and Computation},
issn = {ISSN 1549-9618},
number = {10},
volume = {16},
place = {United States},
publisher = {American Chemical Society},
year = {2020},
month = {09}}
Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, Vol. 454, Issue 1969https://doi.org/10.1098/rspa.1998.0164