1fNoise-An "Infrared" Phenomenon

Abstract

The current carried by a beam of electrons which have been scattered from an arbitrary potential is shown to exhibit fluctuations with a $\frac{1}{f}$ spectrum up to $f=0\mathrm{}$. The exponent of $f$ is smaller than unity by an amount determined by infrared radiative corrections. This amount is essentially the fine-structure constant $\alpha$ and practically coincides with the $\frac{1}{f}$ noise coefficient for one carrier. Similar noise is expected from current carriers in any medium.