Partitioning Quantum Chemistry Simulations with Clifford Circuits

Area of Science:

• Quantum Computing
• Computational Chemistry
• Quantum Information Science

Background:

• Current quantum computing hardware is limited by few, noisy qubits, restricting complex molecular simulations.
• Near-term quantum computers face challenges in performing accurate quantum chemistry calculations for larger molecules.

Purpose of the Study:

• To investigate the limits of classical and near-classical treatment for quantum chemistry calculations within the variational quantum eigensolver framework.
• To develop efficient ansatz for parametrized wavefunctions suitable for near-term quantum hardware.

Main Methods:

• Utilized classically efficient product ansatz, adapting the separable-pair ansatz form.
• Incorporated post-treatment to manage subsystem interactions.
• Employed purely Clifford or near-Clifford circuits to manage Hamiltonian terms and used simulated annealing and genetic algorithms for circuit optimization.

Main Results:

• Demonstrated a method to enhance the capabilities of near-term quantum computers for molecular simulations.
• Showcased the molecule-dependent circuit structure optimization for improved accuracy.
• Investigated the reach and limitations of the proposed methodology on various molecules.

Conclusions:

• The developed approach offers a pathway to perform more complex quantum chemistry calculations on current noisy quantum hardware.
• Physically motivated, classically efficient ansatz combined with optimized circuit structures can mitigate limitations of limited qubit availability.
• Further research can explore the application of this methodology to a broader range of chemical systems.