Constructing Compact ADAPT Unitary Coupled-Cluster Ansatz with Parameter-Based Criterion.

Area of Science:

• Quantum computing
• Computational chemistry
• Quantum algorithms

Background:

• The adaptive derivative-assembled pseudotrotter variational quantum eigensolver (ADAPT-VQE) is a key hybrid quantum-classical algorithm for calculating molecular ground-state energies.
• However, its practical application is limited by redundant excitation operators and high measurement costs.

Purpose of the Study:

• To develop an improved algorithm, Param-ADAPT-VQE, that addresses the scalability limitations of ADAPT-VQE.
• To reduce computational overhead and enhance the accuracy of molecular ground-state energy calculations.

Main Methods:

• Proposed Param-ADAPT-VQE, which selects excitation operators using a parameter-based criterion to avoid redundancy.
• Implemented a sub-Hamiltonian technique and a hot-starting VQE optimization strategy to decrease measurement costs.

Main Results:

• Param-ADAPT-VQE demonstrated superior performance compared to the original ADAPT-VQE.
• Achieved reductions in ansatz size, improved computational accuracy, and significantly lowered measurement costs.
• The algorithm proved compatible with existing ADAPT-VQE frameworks.

Conclusions:

• Param-ADAPT-VQE offers an efficient and scalable enhancement to ADAPT-VQE for molecular quantum chemistry.
• The proposed methods effectively mitigate core obstacles hindering the practical implementation of ADAPT-VQE.