SQUID noise thermometry for nanodevices at submillikelvin temperatures

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).