Fragment molecular orbital-based variational quantum eigensolver for quantum chemistry in the age of quantum...

Area of Science:

• Quantum Computing
• Computational Chemistry
• Quantum Algorithms

Background:

• Quantum computing holds promise for complex system analysis but faces limitations like qubit availability and hardware noise.
• The variational quantum eigensolver (VQE) aims to address these challenges, but its scalability is restricted.
• Existing research focuses on novel ansätze and Hamiltonian modifications to improve VQE performance.

Purpose of the Study:

• To introduce a novel algorithm, Fragment Molecular Orbital/Variational Quantum Eigensolver (FMO/VQE), for efficient quantum chemistry simulations.
• To enhance the scalability of quantum algorithms for molecular simulations by integrating fragment-based approaches.
• To demonstrate the effectiveness of FMO/VQE in reducing qubit requirements while maintaining accuracy.

Main Methods:

• Integration of the Fragment Molecular Orbital (FMO) approach with the Variational Quantum Eigensolver (VQE) algorithm.
• Utilization of the Unitary Coupled Cluster Singles Doubles (UCCSD) ansatz for quantum simulations.
• Application of the FMO/VQE method to molecular systems of varying sizes and basis sets (STO-3G and 6-31G).

Main Results:

• The FMO/VQE algorithm achieved a low absolute error of 0.053 mHa with 8 qubits for a [Formula: see text] system (STO-3G basis set).
• An absolute error of 1.376 mHa was obtained with 16 qubits for a [Formula: see text] system (6-31G basis set).
• Demonstrated significant scalability improvements over conventional VQE, requiring fewer qubits for accurate results.

Conclusions:

• The FMO/VQE method represents a significant advancement in scalable quantum chemistry simulations.
• Integrating fragment-based quantum chemistry with quantum algorithms enhances qubit efficiency and accuracy.
• This approach facilitates more complex molecular simulations, aligning with the progress of quantum computing.