Adaptive construction of shallower quantum circuits with quantum spin projection for fermionic systems

Abstract

Quantum computing is a promising approach to harnessing strong correlation in molecular systems; however, current devices only allow for hybrid quantum-classical algorithms with a shallow circuit depth, such as the variational quantum eigensolver (VQE). In this study, we report the importance of the Hamiltonian symmetry in constructing VQE circuits adaptively. This treatment often violates symmetry, thereby deteriorating the convergence of fidelity to the exact solution, and ultimately resulting in deeper circuits. We demonstrate that symmetry-projection can provide a simple yet effective solution to this problem, by keeping the quantum state in the correct symmetry space, to reduce the overall gate operations. The scheme also reveals the significance of preserving symmetry in computing molecular properties, as demonstrated in our illustrative calculations.

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Cited by in corpus (6)

• Improved algorithms of quantum imaginary time evolution for ground and excited states of molecular systems
• Characterization of variational quantum algorithms using free fermions
• Fermionic Adaptive Sampling Theory for Variational Quantum Eigensolvers
• Stabilizer-Accelerated Quantum Many-Body Ground-State Estimation
• Quantum computing of magnetic-skyrmion-like patterns in Heisenberg ferromagnets
• Mitigating the measurement overhead of ADAPT-VQE with optimised informationally complete generalised measurements