Unbounded 1/f1/f-spectrum from quantum fluctuations of the Coulomb potential at finite temperature

Experimentally observed unboundedness of flicker noise spectrum is explained on the basis of a finite-temperature theory of quantum electromagnetic fluctuations produced by electrons in an external electric field. Account of the photon heat bath and external field effects results in a 1/f1/f-contribution to the power spectrum of fluctuations, which is odd in frequency, and gives rise to a finite contribution to the voltage correlation function. The derived expression is shown to be in agreement with the experimental data on flicker noise measurements in metal films.