Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, FI-00076, Aalto, Finland.
Sci Rep. 2017 Aug 14;7(1):8011. doi: 10.1038/s41598-017-08710-7.
We demonstrate simultaneous measurements of DC transport properties and flux noise of a hybrid superconducting magnetometer based on the proximity effect (superconducting quantum interference proximity transistor, SQUIPT). The noise is probed by a cryogenic amplifier operating in the frequency range of a few MHz. In our non-optimized device, we achieve minimum flux noise ~4 μΦ/Hz, set by the shot noise of the probe tunnel junction. The flux noise performance can be improved by further optimization of the SQUIPT parameters, primarily minimization of the proximity junction length and cross section. Furthermore, the experiment demonstrates that the setup can be used to investigate shot noise in other nonlinear devices with high impedance. This technique opens the opportunity to measure sensitive magnetometers including SQUIPT devices with very low dissipation.
我们展示了基于超导近邻效应（超导量子干涉近邻晶体管，SQUIPT）的混合超导磁强计的直流传输特性和磁通噪声的同时测量。噪声由工作在几兆赫兹频率范围内的低温放大器探测。在我们的非优化器件中，通过探测隧道结的散粒噪声，实现了最小磁通噪声约为 4 μΦ/Hz。通过进一步优化 SQUIPT 参数，主要是最小化近邻结长度和横截面积，可以改善磁通噪声性能。此外，该实验表明，该设置可用于研究具有高阻抗的其他非线性器件中的散粒噪声。该技术为包括具有极低损耗的 SQUIPT 器件在内的灵敏磁强计的测量提供了机会。
