Unitary Block-Correlated Coupled Cluster Ansatz Based on the Generalized Valence Bond Wave Function for Quantum...

Area of Science:

• Quantum Computing
• Computational Chemistry
• Strongly Correlated Systems

Background:

• Strongly correlated systems pose challenges for classical quantum chemistry.
• Quantum computing, via variational quantum eigensolver (VQE), offers potential solutions.
• Current VQE methods like unitary coupled cluster (UCC) are limited by their single-reference nature for these systems.

Purpose of the Study:

• To develop a novel quantum computing ansatz for strongly correlated systems.
• To improve the accuracy and efficiency of quantum simulations for these challenging systems.

Main Methods:

• Introduction of the generalized valence bond-based unitary block correlated coupled cluster (GVB-UBCCC) method.
• Implementation of GVB-UBCCC with up to two-block correlation (GVB-UBCCC2).
• Application to investigate ground-state energies of H4, water dimer, N2H2, and S6 using up to 24 qubits.

Main Results:

• GVB-UBCCC2 achieved more accurate ground-state energies than UCCSD for the studied strongly correlated systems.
• The GVB-UBCCC method exhibits a favorable scaling of O(N^2) quantum gates and parameters.
• This contrasts with the O(N^4) scaling of UCCSD, indicating significant efficiency gains.

Conclusions:

• The GVB-UBCCC method is effective for simulating strongly correlated systems.
• This novel ansatz demonstrates potential advantages in accuracy and computational efficiency for quantum chemistry applications.