Spatial field correlation, the building block of mesoscopic fluctuations

Abstract

The absence of self averaging in mesoscopic systems is a consequence of long-range intensity correlation. Microwave measurements suggest and diagrammatic calculations confirm that the correlation function of the normalized intensity with displacement of the source and detector, $ΔR$ and $Δr$, respectively, can be expressed as the sum of three terms, with distinctive spatial dependences. Each term involves only the sum or the product of the square of the field correlation function, $F \equiv F_{E}^2$. The leading-order term is the product, the next term is proportional to the sum. The third term is proportional to $[F(ΔR)F(Δr) + [F(ΔR)+F(Δr)] + 1]$.