标题： 使用超薄薄膜超导谐振器揭示自旋翻转二能级系统 显示英文标题

标题： Revealing spin-flip two-level systems using ultra-thin film superconducting resonators

摘要： 材料缺陷是固态量子器件中噪声和损耗的主要来源，其行为通常被建模为由相邻位点之间的电荷隧穿形成的双能级系统（TLSs）。然而，它们的自旋在隧穿中的作用及其对器件性能的影响仍鲜有研究。在本工作中，利用超薄TiN超导谐振器，我们通过在低磁场下观察到共振频率的意外增加，揭示了异常的TLS行为。此外，提出了一种自旋翻转TLS模型，其中缺陷自旋产生的不均匀局部磁场产生了有效的自旋-轨道耦合。这种机制将电荷隧穿和自旋翻转混合在一起，定量地再现了观测到的频率-场关系及其温度依赖性。这项工作加深了对自旋依赖的TLS行为的理解，为磁控工程固态量子器件中的噪声和损耗提供了可能性。 显示英文摘要

摘要： Material disorders are one of the major sources of noise and loss in solid-state quantum devices, whose behaviors are often modeled as two-level systems (TLSs) formed by charge tunneling between neighboring sites. However, the role of their spins in tunneling and its impact on device performance remain highly unexplored. In this work, employing ultra-thin TiN superconducting resonators, we reveal anomalous TLS behaviors by demonstrating an unexpected increase in resonant frequency at low magnetic fields. Furthermore, a spin-flip TLS model is proposed, in which an effective spin-orbit coupling is generated by inhomogeneous local magnetic fields from defect spins. This mechanism mixes charge tunnelings and spin flips, quantitatively reproducing the observed frequency-field relationship and its temperature dependence. This work deepens the understanding of spin-dependent TLS behaviors, offering the possibility of magnetically engineering noise and loss in solid-state quantum devices.