Quantum Theory of Flicker Noise in Metal Films

TL;DR

This paper develops a quantum electromagnetic fluctuation model to explain flicker noise in metal films, linking the noise spectrum's frequency exponent to quantum backreaction effects and effective dimensionality, matching experimental observations.

Contribution

It introduces a quantum theory incorporating effective dimensionality to explain deviations in flicker noise spectra in metal films, providing a comprehensive analytical framework.

Findings

Derived a 1/f^gamma spectrum from quantum electromagnetic fluctuations.

Linked frequency exponent deviation to quantum backreaction and dimensionality.

Matched theoretical predictions with experimental flicker noise data.

Abstract

Flicker (1/f^gamma) voltage noise spectrum is derived from finite-temperature quantum electromagnetic fluctuations produced by elementary charge carriers in external electric field. It is suggested that deviations of the frequency exponent \gamma from unity, observed in thin metal films, can be attributed to quantum backreaction of the conducting medium on the fluctuating field of the charge carrier. This backreaction is described phenomenologically in terms of the effective momentum space dimensionality, D. Using the dimensional continuation technique, it is shown that the combined action of the photon heat bath and external field results in a 1/f^gamma-contribution to the spectral density of the two-point correlation function of electromagnetic field. The frequency exponent is found to be equal to 1 + delta, where delta = 3 - D is a reduction of the momentum space dimensionality. This result is applied to the case of a biased conducting sample, and a general expression for the voltage power spectrum is obtained which possesses all characteristic properties of observed flicker noise spectra. The range of validity of this expression covers well the whole measured frequency band. Gauge independence of the power spectrum is proved. It is shown that the obtained results naturally resolve the problem of divergence of the total noise power. A detailed comparison with the experimental data on flicker noise measurements in metal films is given.