名义立方对称$^{229}$Th位点处无序诱导的核跃迁双重态
Disorder-induced nuclear-transition doublet at nominally cubic $^{229}$Th sites
- University of Nevada, Reno（内华达大学雷诺分校）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究针对名义立方对称$^{229}$Th位点的核钟跃迁非均匀展宽问题，揭示稀静态点缺陷无序诱导的双重态特征，结合掺杂晶体实验数据，提出可作为核钟鉴别器的潜在凹陷。
AI中文摘要：
即使在理想晶格电场梯度为零的名义立方对称位点，$^{229}$Th核钟跃迁仍存在非均匀展宽。研究表明，稀静态点缺陷无序会产生一个双重态，其在无四极矩频率处存在零点；该双重态在各向同性近似下对称，尺寸失配点缺陷会引入小的瓣状不对称性但不消除零点。带电缺陷与尺寸失配缺陷遵循逆立方标度，且具有近似共同的归一化轮廓，其宽度可分为基质控制的背景项和与$^{229}$Th密度线性相关的项。在重掺杂$^{229}$Th:CaF$_2$晶体[Nature 657, 626 (2026)]中，钍相关贡献与测得的1.1 MHz宽度相当；在轻掺杂晶体[arXiv:2606.08870]中，0.9 MHz宽度限定了基质背景。两种晶体的光谱均未出现预测的凹陷，表明两者均存在扩展缺陷；若该凹陷被观测到，可作为参考无四极矩核跃迁频率的核钟鉴别器。
英文摘要：
The $^{229}$Th nuclear clock transition is inhomogeneously broadened even at sites of nominally cubic symmetry, where the electric-field gradient of the ideal lattice vanishes. We show that dilute static point-defect disorder produces a doublet with a zero at the quadrupole-free frequency. The doublet is symmetric in the isotropic approximation; size misfit point defects introduce a small lobe asymmetry without removing the zero. Charged and size-misfit defects share inverse-cube scaling and an approximately common normalized profile, whose width separates into a host-controlled background and a term linear in the $^{229}$Th density. In a heavily doped $^{229}$Th:CaF$_2$ crystal [Nature 657, 626 (2026)], the thorium-linked contribution is comparable to the measured 1.1 MHz width; in a lightly doped crystal [arXiv:2606.08870], the 0.9 MHz width bounds the host background. Neither spectrum shows the predicted dip, which points to the presence of extended defects in both crystals. If the predicted dip is resolved, it can provide a nuclear-clock discriminator referenced to the quadrupole-free nuclear transition frequency.
