Accuracy and Resource Estimations for Quantum Chemistry on a Near-Term Quantum Computer

Area of Science:

• Molecular quantum chemistry
• Quantum computing
• Computational chemistry

Background:

• Accurate prediction of chemical reactivity is crucial for molecular quantum chemistry.
• Large-scale quantum computers promise efficient electronic structure calculations.
• Near-term quantum devices are limited by noise and qubit count.

Purpose of the Study:

• To implement and assess the Unitary Coupled-Cluster Variational Quantum Eigensolver (UCCSD-VQE) for both open- and closed-shell molecules.
• To evaluate the accuracy of UCCSD-VQE for molecular energies and chemical reactions.
• To estimate quantum hardware requirements for practical applications.

Main Methods:

• Implementation of the UCCSD-VQE algorithm.
• Testing on nine small molecular systems and four chemical reactions.
• Comparison with established methods like coupled-cluster and density functional theory.

Main Results:

• The UCCSD-VQE implementation successfully treats both open- and closed-shell molecules.
• Energy calculations show good accuracy when compared to classical methods.
• Initial estimates for required quantum hardware resources were made.

Conclusions:

• UCCSD-VQE is a promising hybrid quantum-classical approach for near-term quantum computers.
• The method demonstrates potential for accurate chemical reactivity predictions.
• Further development and hardware advancements are needed for large-scale practical use.