Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs
Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs
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DOI：
10.1109/tasc.2014.2364920
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发表时间：
2015-06
影响因子：
1.8
通讯作者：
T. Patel;B. Li;J. Gallop;D. Cox;K. Kirkby;E. Romans;J. Chen;A. Nisbet;L. Hao
中科院分区：
文献类型：
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作者：
T. Patel;B. Li;J. Gallop;D. Cox;K. Kirkby;E. Romans;J. Chen;A. Nisbet;L. Hao
由Nb薄膜制成的NanoSQUID已被生产出纳米环尺寸低至200 nm，使用尺寸小于60 nm的弱连接结。这些复合（W/Nb）单层薄膜器件通过FIB铣削图案化，在5至8.5 K之间的温度下显示出非常好的低噪声性能~170 nΦ 0，并且可以在相当高的磁场（至少高达1 T）下工作。迄今为止生产的器件具有有限的工作温度范围，通常只有1-2 K。我们的目标是在4.2 K下实现操作，与最好的SQUID系列阵列（SSA）兼容。使用SSA读出nanoSQUID为我们提供了一种研究前者固有噪声的方法。在本文中，我们报告这些nanoSQUID的改进的白色噪声水平，使潜在的检测在1 Hz的带宽中的单个电子自旋翻转。在低频时，噪声性能已经受到SSA噪声的限制。
NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ~170 nΦo at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T) . The devices produced so far have a limited operating temperature range, typically only 1-2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise.