Which options exist for NISQ-friendly linear response formulations?

Abstract

Linear response (LR) theory is a powerful tool in classic quantum chemistry crucial to understanding photo-induced processes in chemistry and biology. However, performing simulations for large systems and in the case of strong electron correlation remains challenging. Quantum computers are poised to facilitate the simulation of such systems, and recently, a quantum linear response formulation (qLR) was introduced. To apply qLR to near-term quantum computers beyond a minimal basis set, we here introduce a resource-efficient qLR theory using a truncated active-space version of the multi-configurational self-consistent field LR ansatz. Therein, we investigate eight different near-term qLR formalisms that utilize novel operator transformations that allow the qLR equations to be performed on near-term hardware. Simulating excited state potential energy curves and absorption spectra for various test cases, we identify two promising candidates dubbed ``proj LRSD'' and ``all-proj LRSD''.

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Cited by in corpus (9)

• Quantum Equation of Motion with Orbital Optimization for Computing Molecular Properties in Near-Term Quantum Computing
• Subspace methods for the simulation of molecular response properties on a quantum computer
• Reduced density matrix formulation of quantum linear response
• Understanding and mitigating noise in molecular quantum linear response for spectroscopic properties on quantum computers
• Divergences in classical and quantum linear response and equation of motion formulations
• Determining the N-representability of a reduced density matrix via unitary evolution and stochastic sampling
• Self-consistent Quantum Linear Response with a Polarizable Embedding environment
• Equation-of-motion internally contracted multireference unitary coupled-cluster theory
• Determining the ensemble N-representability of Reduced Density Matrices