论文标题
基于亚微米大小的约瑟夫森连接的超敏感鱿鱼
Towards ultra-sensitive SQUIDs based on sub-micrometer-sized Josephson Junctions
论文作者
论文摘要
我们最近展示了一个1 $^{\ textrm {st}} $ - 订购轴向渐变级鱿鱼系统，该系统在他的液体中操作，其液体效果可忽略不计。 $ \ sim 30 \，h $接近鱿鱼限制的耦合能量敏感性$ \ varepsilon_ {c} $对应于180〜180〜的白色场噪声，at〜hz $ {^^{ - 1/2}}} $。为了进一步提高鱿鱼噪声性能，通过将其横向尺寸从$ 2.5〜μ $ m降低到低于$ 1〜μ $ m，可以减少连接电容。这是通过将基于HFTI自换连接技术的亚微米大小的Josephson连接的制造过程来实现的，它使用Alo $ _ {\ textrm {x}} $作为绝缘层的SIS过程。我们的能量灵敏度分别为4.7 $ \，H $和20 $ \，h $ 4.2〜K，分别为未偶联和耦合鱿鱼。我们还研究了未耦合鱿鱼的噪声的温度依赖性，并在400 〜MK处的白噪声状态下达到了0.65 $ \，H $的能量灵敏度。
We recently demonstrated a 1$^{\textrm{st}}$-order axial gradiometer SQUID system, which is operated in a liquid He dewar with negligible noise contribution. The achieved close to SQUID-limited measured coupled energy sensitivity $\varepsilon_{c}$ of $\sim 30\,h$ corresponds to a white field noise below 180~aT~Hz${^{-1/2}}$. In order to further improve the SQUID noise performance, the junction capacitance was reduced by decreasing its lateral size from $2.5~μ$m to below $1~μ$m. This was realized by extending the fabrication process for submicrometer-sized Josephson Junctions based on the HfTi self-shunted junction technology to an SIS process with AlO$_{\textrm{x}}$ as the insulating layer. We achieved energy sensitivities of 4.7$\,h$ and 20$\,h$ at 4.2~K for uncoupled and coupled SQUIDs, respectively. We also investigated the temperature dependence of the noise of the uncoupled SQUIDs and reached an energy sensitivity of 0.65$\,h$ in the white noise regime at 400~mK.
