Event Details

An Experimental Demonstration of Nanoelectronic Electron Temperatures Below 1 mK

Extending the experimental temperature domain of nanoelectronic devices into the microkelvin regime would make novel quantum states of matter accessible with great potential for quantum technologies. Cooling bulk metals to microkelvin temperatures by adiabatic demagnetization of nuclear spins has been an established technique for decades, however reaching electron temperatures below 1 mK in nanofabricated devices remained an unsolved challenge up until now.This is due to the thermal decoupling of electrons in micro- and nanostructures from the cold substrate in combination with high frequency electronic noise directly heating the electron system. We demonstrate the first nuclear magnetic cooling of electrons to microkelvin temperatures in a nanofabricated device, achieved by integrating indium as the nuclear refrigerant onto the metallic islands of a Coulomb blockade thermometer with the device leads attached to an "N+1" parallel network of indium refrigerant based nuclear cooling stages. By performing the nuclear demagnetization process, we demonstrate electron temperatures below 500 µK by primary electron thermometry, and show that the device stays below 1mK for several days.