Ultra-sensitive cryogenic thermometer based on an array of the SIN tunnel junctions

A novel concept of an ultra-sensitive thermometer based on a series array of superconductor–insulator–normal (SIN) tunnel junctions has been proposed. The array helps to improve matching with an amplifier proportionally to the number of junctions. There is no fundamental limit for total noise and the main limitation is electron–phonon noise of the normal island reverse proportional to volume of the normal metal.