Vibrations play a prominent role in magnetic relaxation processes of molecular spin qubits as they couple to spin states, leading to the loss of quantum information. Direct experimental determination of vibronic coupling is crucial to understand and control the spin dynamics of these nano-objects, which represent the limit of miniaturization for quantum devices. Herein, we measure the magneto-infrared properties of the molecular spin qubit system Na₉[Ho(W₅O₁₈)₂]·35H₂O. Our results place significant constraints on the pattern of crystal field levels and the vibrational excitations allowing us to unravel vibronic decoherence pathways in this system. We observe field-induced spectral changes near 63 and 370 cm^–1 that are modeled in terms of odd-symmetry vibrations mixed with f-manifold crystal field excitations. The overall extent of vibronic coupling in Na₉[Ho(W₅O₁₈)₂]·35H₂O is limited by a modest coupling constant (on the order of 0.25) and a transparency window in the phonon density of states that acts to keep the intramolecular vibrations and M_J levels apart. These findings advance the understanding of vibronic coupling in a molecular magnet with atomic clock transitions and suggest strategies for designing molecular spin qubits with improved coherence lifetimes.

中文翻译：

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分子自旋量子比特中振动弛豫通路的光谱分析 [Ho(W5O18)2]9–：稀疏光谱是关键

振动在分子自旋量子位的磁弛豫过程中起着重要作用，因为它们与自旋态耦合，导致量子信息的丢失。振动耦合的直接实验测定对于理解和控制这些纳米物体的自旋动力学至关重要，这代表了量子器件小型化的极限。在此，我们测量了分子自旋量子位系统 Na ₉ [Ho(W ₅ O ₁₈ ) ₂ ]·35H ₂ O的磁红外特性。我们的结果对晶体场能级的模式和振动激发产生了重大限制，使我们能够解开该系统中的振动退相干通路。我们在 63 和 370 cm 附近观察到场引起的光谱变化^–1根据奇对称振动与f流形晶体场激发混合建模。Na ₉ [Ho(W ₅ O ₁₈ ) ₂ ]·35H ₂ O中振动耦合的总体范围受到适度耦合常数（大约为 0.25）和声子态密度中的透明窗口的限制，该窗口作用于保持分子内振动和M _J水平分开。这些发现促进了对具有原子钟跃迁的分子磁体中的振动耦合的理解，并提出了设计具有改进相干寿命的分子自旋量子位的策略。