Dual exponential coupled cluster theory: Unitary adaptation, implementation in the variational quantum eigensolver...

Area of Science:

• Quantum Computing
• Quantum Chemistry
• Computational Chemistry

Background:

• Strong correlation in molecules presents a significant challenge for classical computational methods.
• Existing quantum chemistry theories often struggle with arbitrary electronic complexity.

Purpose of the Study:

• To develop a unitary variant of double exponential coupled cluster theory for strong correlation.
• To implement this theory on a hybrid quantum-classical variational quantum eigensolver framework.

Main Methods:

• Developed a sequential product of parameterized unitary Ansätze.
• Utilized a shallow quantum circuit within the variational quantum eigensolver.
• Introduced approximations for scattering operators in Ansatz variants.

Main Results:

• The method effectively handles molecular strong correlation with arbitrary electronic complexity.
• Implementation on a quantum computer bypasses classical computational bottlenecks.
• Proposed schemes perform uniformly well across molecular potential energy surfaces.

Conclusions:

• The developed unitary coupled cluster variant is a promising approach for strongly correlated systems.
• Hybrid quantum-classical methods offer a viable path for complex electronic structure calculations.
• The approach shows comparable performance to conventional methods with reduced computational cost.