Lanthanide-based spin qubits are intriguing candidates for high-fidelity quantum memories owing to their spin-optical interfaces. Metal–organic frameworks (MOFs) offer promising solid-state platforms to host lanthanide ions because their bottom-up synthesis enables rational optimization of both spin coherence and luminescence. Here, we incorporated Nd³⁺ and Gd³⁺ into a La³⁺-based MOF with various doping levels and examined their qubit performance including the spin relaxation time (T₁) and phase memory time (T_m). Both Nd³⁺ and Gd³⁺ behave as spin qubits with T₁ exceeding 1 ms and T_m approaching 2 μs at 3.2 K at low doping levels. Variable-temperature spin dynamic studies unveiled spin relaxation and decoherence mechanisms, highlighting the critical roles of spin–phonon coupling and spin–spin dipolar coupling. Accordingly, reducing the spin concentration, spin–orbit coupling strength, and ground spin state improves the qubit performance of lanthanide-based MOFs. These optimization strategies serve as guidelines for the future development of solid-state lanthanide qubits targeting quantum information technologies.

中文翻译：

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优化基于镧系元素的金属有机框架的自旋量子比特性能


基于镧系元素的自旋量子比特由于其自旋光学接口而成为高保真量子存储器的有趣候选者。金属-有机框架 （MOF） 为镧系元素离子提供了有前途的固态平台，因为它们的自下而上的合成能够合理优化自旋相干和发光。在这里，我们将 Nd³⁺ 和 Gd³⁺ 合并到具有不同掺杂水平的基于 La³⁺ 的 MOF 中，并检查了它们的量子比特性能，包括自旋弛豫时间 （T₁） 和相位存储时间 （T_m）。Nd³⁺ 和 Gd³⁺ 都表现为自旋量子比特，在低掺杂水平下，T₁ 超过 1 ms，T _m 在 3.2 K 下接近 2 μs。变温自旋动力学研究揭示了自旋弛豫和退相干机制，突出了自旋-声子耦合和自旋-自旋偶极耦合的关键作用。因此，降低自旋浓度、自旋-轨道耦合强度和基自旋态可以提高基于镧系元素的 MOF 的量子比特性能。这些优化策略为未来针对量子信息技术的固态镧系元素量子比特的发展提供了指导。