Jastrow-type Decomposition in Quantum Chemistry for Low-Depth Quantum Circuits.

Area of Science:

• Quantum Computing
• Computational Chemistry
• Quantum Algorithms

Background:

• Near-term quantum computers require efficient algorithms for accurate chemical simulations.
• Existing methods often rely on approximations like Trotterization, limiting precision.

Purpose of the Study:

• To develop a novel, efficient ansatz for quantum computation of molecular energies.
• To achieve near or exact full-configuration interaction (CI) energies.

Main Methods:

• Proposed an O(N^2)-parameter ansatz using unitary cluster Jastrow operators.
• Derived the ansatz from T2 amplitudes of unitary coupled cluster with generalized singles and doubles (uCCGSD).
• Utilized commutative Pauli operator products (Jordan-Wigner strings) to avoid Trotter approximation.

Main Results:

• The ansatz can reproduce uCCGSD energies and approach full-CI energy.
• Demonstrated accuracy for nitrogen dimer dissociation via quantum circuit simulations.
• Compared performance against other O(N^2)-parameter ansatzs.

Conclusions:

• The proposed ansatz is a strong candidate for variational quantum eigensolver algorithms on near-term quantum devices.
• The method offers a path to highly accurate quantum chemical calculations without Trotter errors.