标题： 量子硬件上化学系统模拟中的耦合簇下约化理论 显示英文标题

标题： Coupled Cluster Downfolding Theory in Simulations of Chemical Systems on Quantum Hardware

摘要： 量子技术在化学问题中的实际应用面临重大挑战，特别是在处理现实基础集和准确包含电子相关效应方面。 由于逻辑量子比特的数量、保真度以及现有硬件支持的浅层电路深度的限制，目前直接解决这些问题的方法不可行；所有这些因素都阻碍了在所需精度水平上的模拟。 一种有希望的替代方法是混合量子-经典计算，其中经典资源用于构建符合当前量子设备约束的有效哈密顿量。 在本文中，我们展示了混合方法的性能：首先在低维活性空间中评估耦合簇下约化哈密顿量，并随后使用量子算法计算相应的基态能量。 我们的全面分析探讨了当数百个轨道被下约化为当今量子硬件可处理的问题规模时，恢复相关能量的可达精度。 我们认为，这种灵活的混合算法，其问题规模可以根据可用的量子资源进行调整，可以作为噪声中等规模量子（NISQ）设备和未来容错量子计算机之间的桥梁，标志着在化学领域早期实现量子优势的一步。 显示英文摘要

摘要： The practical application of quantum technologies to chemical problems faces significant challenges, particularly in the treatment of realistic basis sets and the accurate inclusion of electron correlation effects. A direct approach to these problems is currently infeasible due to limitations in the number of logical qubits, their fidelity, and the shallow circuit depths supported by existing hardware; all of which hinder simulations at the required level of accuracy. A promising alternative is hybrid quantum-classical computing, where classical resources are used to construct effective Hamiltonians characterized by dimensions that conform to the constraints of current quantum devices. In this paper, we demonstrate the performance of a hybrid approach: coupled-cluster downfolded Hamiltonians are first evaluated in reduced-dimensionality active spaces, and the corresponding ground-state energies are subsequently computed using quantum algorithms. Our comprehensive analysis explores the achievable accuracy in recovering correlation energies when hundreds of orbitals are downfolded into a problem size tractable by today's quantum hardware. We argue that such flexible hybrid algorithms, where problem size can be tailored to available quantum resources, can serve as a bridge between noisy intermediate-scale quantum (NISQ) devices and future fault-tolerant quantum computers, marking a step toward the early realization of quantum advantage in chemistry.