Giorgio De Simoni

An ordinary ultra-sensitive magnetic field sensor is like a scale that starts lying when you put too heavy a weight on it. The signal becomes distorted, and you have to add complex electronics to straighten out the readings. That electronics adds noise and slows things down. The new sensor, bi-SQUIPT, works differently.

A thin film of indium arsenide on an insulating substrate behaves like a double-walled thermos: the electrons inside barely give off heat to the surrounding crystal. In an ordinary metal, electrons quickly exchange energy with atomic vibrations, so their temperature is always close to that of the sample.