SQUID noise thermometry for nanodevices at submillikelvin temperatures

在这个项目中，博士生将在超低温组工作，设计、构建和研究基于超导量子干涉器件（SQUID）的纳米器件噪声测温。将微纳米样品冷却到亚毫开尔文温度的需求非常大，而ULT目前保持着在纳米样品中冷却电子的世界纪录。冷却是通过将纳米样品浸入液态氦-3或通过纳米样品的直接绝热退磁来完成的。突出的挑战是准确、可靠和快速地测量温度。前所未有的SQUID灵敏度将使我们能够开发一种非接触式温度计，测量金属纳米样品中电子振荡引起的磁噪声。噪声的量是温度相关的，可以从第一原理计算，这使得温度计可以自我校准。我们的目标是使用SQUID双通道之间的相互关系来消除SQUID放大器的任何噪声，从而使其工作温度降低到亚毫开尔文（~50微开尔文）。

In this project, the PhD student will work within the Ultra Low Temperature group to design, build and investigate Superconducting Quantum Interference Device (SQUID) based noise thermometry for nanodevices. There is a huge demand for cooling micro and nano-sized samples down to submillikelvin temperatures and ULT currently holds world record on cooling electrons in nano samples. Cooling is accomplished either by submerging nano samples in liquid helium-3 or by the direct adiabatic demagnetization of nano samples. The outstanding challenge is to measure temperature accurately, reliably and fast. Unprecedented SQUID sensitivity will permit us developing a non-contact thermometer measuring magnetic noise raising from the oscillations of the electrons in the metallic nano samples. The amount of noise is temperature-dependent and can be calculated from the first principles, which allows the thermometer to be self-calibrated. We aim to use cross-correlation between SQUID two-channels to eliminate any noise from the SQUID amplifier thus making it operational down to submillikelvin temperatures (~50 microkelvins).