用理论化学设计量子技术用的鲁棒分子自旋
Designing robust molecular spins for quantum technologies with theoretical chemistry
AI总结：
本章结合理论化学方法，通过从头算电子结构与开放量子系统动力学，为设计长寿命分子量子比特提供了指导原则，平衡了计算成本与准确性。
AI中文摘要：
分子自旋是量子信息科学的通用平台，具备化学可调、可寻址量子比特的潜力，但实现这一目标需要理解并抑制量子退相干。本章提供了当前先进化学理论的理论概述，该理论将从头算电子结构与开放量子系统动力学相结合，用于指导长寿命分子量子比特的合理设计。从电子层面开始，讨论了用于参数化有效自旋哈密顿量的多参考和相对论电子结构方法，主要聚焦于准确捕获g张量、零场分裂和超精细相互作用。这些参数被输入自旋-声子和自旋-自旋耦合模型，以量化不同环境下的T₁和T₂弛豫。本章评估了从因子化到矩阵乘积态方法的动力学方法层级，平衡计算成本与准确性及泛化性。最终，将这些理论模型映射到分子结构可建立设计原则，如同位素取代和空间自旋离域，以理解并延长相干寿命。
英文摘要：
Molecular spins represent a versatile platform for quantum information science, with the potential to offer chemically tunable, addressable qubits. However, achieving this requires understanding and mitigating quantum decoherence. This Chapter provides a theoretical overview of current state-of-the-art chemical theory connecting ab initio electronic structure with open quantum system dynamics to guide the rational design of long-lived molecular qubits. Beginning at the electronic level, multi-reference and relativistic electronic structure methods to parameterize effective spin Hamiltonians are discussed, with a primary focus on accurately capturing $g$-tensors, zero-field splitting, and hyperfine interactions. These parameters feed into models of spin-phonon and spin-spin coupling to quantify $T_1$ and $T_2$ relaxation across various environmental regimes. This Chapter evaluates a hierarchy of dynamical methods, ranging from factorization to matrix product state approaches, balancing computational cost against accuracy and generalizability. Ultimately, mapping these theoretical models to molecular architecture can establish design principles, such as isotopic substitution and spatial spin delocalization, to understand and extend coherence lifetimes.
