AI 中文总结
该研究结合计算与实验，揭示掺Er$^{3+}$的CeO$_2$自旋量子比特平台中，Ce$^{3+}$极化子及其复合物是光学退相干的来源，为改进该量子平台提供了缺陷工程目标。
AI 中文摘要
二氧化铈（CeO$_2$）中的铒离子（Er$^{3+}$）是量子通信领域极具潜力的自旋-光子接口，但限制其光学相干性的机制仍未被充分理解。研究人员采用带有限尺寸修正的周期性杂化密度泛函理论计算，发现Ce$^{3+}$极化子及其与氧空位、Er$^{3+}$掺杂剂形成的复合物是光学退相干的可能来源。这些缺陷在0.8 eV能量下具有有限的光电离截面，与实验中使用的激光激发能量以及Er$^{3+}$的发射能量相吻合，这种共振会导致极化子发生光电离，并使Er$^{3+}$的光致发光猝灭，进而引发光学线宽展宽、激发态寿命缩短以及电荷噪声产生。研究人员对掺Er$^{3+}$的CeO$_2$薄膜在0.8 eV光照下开展了浓度依赖型光电流测量，验证了所预测的退相干路径。该研究结合计算与实验结果，为改进掺Er$^{3+}$的CeO$_2$平台明确了具体的缺陷工程目标，并指出该退相干机制可能与其他掺Er$^{3+}$的多价氧化物量子平台相关。
英文摘要
Erbium ions (Er$^{3+}$) in cerium dioxide (CeO$_2$) represent a promising spin-photon interface for quantum communication, but the mechanisms limiting their optical coherence remain poorly understood. Using periodic hybrid density functional theory calculations with finite-size corrections, we identify Ce$^{3+}$ polarons and their complexes with oxygen vacancies and Er$^{3+}$ dopants as likely sources of optical decoherence. These defects exhibit finite photoionization cross-sections at 0.8 eV, coinciding with both the laser excitation energy used experimentally and the emission energy of Er$^{3+}$. This resonance enables photoionization of the polarons and photoluminescence quenching of Er$^{3+}$, leading to the broadening of optical linewidths, shortening of excited-state lifetimes, and introduction of charge noise. Our concentration-dependent photocurrent measurements in Er$^{3+}$-doped CeO$_2$ films under 0.8 eV illumination validate the predicted decoherence pathway. Our combined computational and experimental results identify a concrete defect-engineering target for improving the Er$^{3+}$-doped CeO$_2$ platform, and point to a decoherence mechanism likely relevant to other Er$^{3+}$-doped multivalent-oxide quantum platforms.
Comments7 pages, 4 figures
