Modular Cluster Circuits for the Variational Quantum Eigensolver.

Area of Science:

• Quantum Computing
• Computational Chemistry
• Quantum Algorithms

Background:

• The variational quantum eigensolver (VQE) is a popular algorithm for computing molecular properties on noisy intermediate-scale quantum (NISQ) devices.
• Minimizing quantum circuit depth is crucial to mitigate noise accumulation in NISQ devices.

Purpose of the Study:

• Introduce a novel modular 2-qubit cluster circuit for VQE.
• Achieve shallow-depth quantum circuits without sacrificing chemical accuracy.
• Provide a valence bond chemical interpretation for the circuit design.

Main Methods:

• Designed a modular 2-qubit cluster circuit architecture.
• Implemented and tested the circuit on various molecular systems (H2, (H2)2, LiH) and the transverse-field Ising model.
• Analyzed circuit depth and chemical accuracy compared to existing methods.

Main Results:

• The proposed cluster circuit enables significantly shallower quantum circuits than previous architectures.
• The design maintains high chemical accuracy in quantum chemical property calculations.
• A clear valence bond interpretation was established for the cluster circuit.

Conclusions:

• The modular 2-qubit cluster circuit offers an efficient approach for VQE on NISQ devices.
• This method reduces noise impact and enhances the feasibility of quantum chemistry simulations.
• The circuit's simplicity and interpretability facilitate further development in quantum algorithms.