Quantum Fluctuations of the Coulomb Potential as a Source of the Flicker Noise

The spectrum of quantum fluctuations of the electromagnetic field produced by quantized matter is determined. It is found that in a wide range of practically important frequencies, the spectral density of fluctuations exhibits an inverse frequency dependence. The magnitude of fluctuations produced by a conducting sample has a Gaussian distribution around its mean value which is inversely proportional to the sample volume. A semi-quantitative estimate shows that the found noise level is in a reasonable agreement with experimental data.