Magnetic field dependence of the internal quality factor and noise performance of lumped-element kinetic inductance detectors
Magnetic field dependence of the internal quality factor and noise performance of lumped-element kinetic inductance detectors
复制标题
集总元件动感电感探测器的内部品质因数和噪声性能的磁场依赖性
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
J. Zmuidzinas
中科院分区：
文献类型：
--
作者：
D. Flanigan;Bradley R. Johnson;M. Abitbol;S. Bryan;R. Cantor;P. Day;Glenn Jones;P. Mauskopf;H. McCarrick;Amber D. Miller;J. Zmuidzinas
我们提出了一种技术，用于增加动态电感检测器（KIDS）的内部品质因数的归零环境磁场与适当施加的磁场。本研究中使用的KID由薄膜铝制成，它们安装在由散装铝制成的不透光封装内，并且它们在接近150美元的价格下运行。由于薄膜铝具有略微升高的临界温度（$T_mathrm{c} = 1.4，mathrm{K}$），因此它在封装（$T_mathrm{c} = 1.2，mathrm{K}$）之前转变，封装也用作磁屏蔽。在冷却时，小至约30 μ T的环境磁场可在薄膜铝转变时在薄膜铝中产生涡流，因为散装铝封装尚未转变，因此尚未屏蔽。这些涡流被困在低于1.2美元的铝封装内，mathrm{K}$并最终在薄膜超导谐振器中产生低的内部品质因子。我们表明，通过控制薄膜过渡时存在的磁场的强度，我们可以控制谐振器的内部品质因数。我们还比较了存在和不存在涡流的噪声性能，并且没有发现超出放大器噪声增加的额外噪声的证据，这是随着损耗增加而预期的。
We present a technique for increasing the internal quality factor of kinetic inductance detectors (KIDs) by nulling ambient magnetic fields with a properly applied magnetic field. The KIDs used in this study are made from thin-film aluminum, they are mounted inside a light-tight package made from bulk aluminum, and they are operated near $150 , mathrm{mK}$. Since the thin-film aluminum has a slightly elevated critical temperature ($T_mathrm{c} = 1.4 , mathrm{K}$), it therefore transitions before the package ($T_mathrm{c} = 1.2 , mathrm{K}$), which also serves as a magnetic shield. On cooldown, ambient magnetic fields as small as approximately $30 , mathrm{mu T}$ can produce vortices in the thin-film aluminum as it transitions because the bulk aluminum package has not yet transitioned and therefore is not yet shielding. These vortices become trapped inside the aluminum package below $1.2 , mathrm{K}$ and ultimately produce low internal quality factors in the thin-film superconducting resonators. We show that by controlling the strength of the magnetic field present when the thin film transitions, we can control the internal quality factor of the resonators. We also compare the noise performance with and without vortices present, and find no evidence for excess noise beyond the increase in amplifier noise, which is expected with increasing loss.