Evaluating Variational Quantum Eigensolver Approaches for Simplified Models of Molecular Systems: A Case Study on...

Area of Science:

• Quantum Computing
• Computational Chemistry
• Molecular Physics

Background:

• The Variational Quantum Eigensolver (VQE) is a hybrid quantum-classical algorithm designed to find the ground-state energy of molecular systems.
• Accurate determination of molecular ground states is crucial for understanding chemical reactions and properties.

Purpose of the Study:

• To investigate the ground state of protocatechuic acid using the VQE algorithm.
• To evaluate the performance of different Ansatzes and active spaces within the VQE framework.
• To compare VQE results with established computational chemistry methods like CISD and FCI.

Main Methods:

• Application of the Variational Quantum Eigensolver (VQE) algorithm.
• Exploration of various Ansatzes, including Unitary Coupled Cluster Singles and Doubles (UCCSD) and Hardware-Efficient Ansatzes.
• Selection of different active spaces for the molecular system.
• Comparison of VQE results against Configuration Interaction Singles Doubles (CISD) and Full Configuration Interaction (FCI) benchmarks.

Main Results:

• VQE, particularly with UCCSD and Hardware-Efficient Ansatzes, demonstrated high accuracy comparable to FCI.
• The choice of Ansatz and active space significantly impacts VQE's performance and accuracy.
• The study successfully applied VQE to the protocatechuic acid molecule.

Conclusions:

• VQE is a robust and effective method for calculating molecular ground-state energies.
• Optimizing Ansatz design and active space selection is critical for maximizing VQE accuracy and efficiency.
• The findings provide valuable insights into the practical application and limitations of VQE in computational chemistry.