Microwave response of vortices in superconducting thin films of Re and Al
Microwave response of vortices in superconducting thin films of Re and Al
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DOI：
10.1103/physrevb.79.174512
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发表时间：
2008-12
影响因子：
3.7
通讯作者：
C. Song;T. Heitmann;M. Defeo;K. Yu;R. McDermott;M. Neeley;J. Martinis;B. Plourde
中科院分区：
文献类型：
--
作者：
C. Song;T. Heitmann;M. Defeo;K. Yu;R. McDermott;M. Neeley;J. Martinis;B. Plourde
在微波频率下驱动的超导体中的涡旋表现出与涡旋粘性、钉扎强度和磁通蠕动效应之间的相互作用有关的响应。与此同时，超导微波谐振电路中的涡旋捕获会导致额外的损耗，并可能导致品质因数的大幅降低。因此，理解超导薄膜中的微波涡旋响应对于设计这种电路（包括超导量子比特和光子探测器）非常重要，这些电路通常在小但非零的磁场中工作。通过冷却领域的顺序为100 $\mu$T及以下，我们的特点是磁场和频率的依赖性的微波响应的小密度的涡流在谐振器由薄膜的Re和Al，这是常用的材料在超导微波电路。当超过一定的阈值冷却场（Re和Al膜的阈值冷却场不同）时，涡旋就会被困在谐振器中。在铝谐振器中的涡流贡献更大的损失，更强烈的磁通蠕动效应比Re谐振器的影响。这种不同的行为可以在一个通用的涡旋动力学模型的框架内描述。
Vortices in superconductors driven at microwave frequencies exhibit a response related to the interplay between the vortex viscosity, pinning strength, and flux creep effects. At the same time, the trapping of vortices in superconducting microwave resonant circuits contributes excess loss and can result in substantial reductions in the quality factor. Thus, understanding the microwave vortex response in superconducting thin films is important for the design of such circuits, including superconducting qubits and photon detectors, which are typically operated in small, but non-zero, magnetic fields. By cooling in fields of the order of 100 $\mu$T and below, we have characterized the magnetic field and frequency dependence of the microwave response of a small density of vortices in resonators fabricated from thin films of Re and Al, which are common materials used in superconducting microwave circuits. Above a certain threshold cooling field, which is different for the Re and Al films, vortices become trapped in the resonators. Vortices in the Al resonators contribute greater loss and are influenced more strongly by flux creep effects than in the Re resonators. This different behavior can be described in the framework of a general vortex dynamics model.