Remarks on the Nyquist and Callen-Welton Theorems

Abstract

The connection of the Callen-Welton and Nyquist fluctuation-dissipation relations is considered for plasma-like classical and quantum systems. The conditions for appearance of the dissipative parameters in the equilibrium current-current correlation function are investigated. The paper presents the arguments for the restrictions of the Nyquist theorem and against violation of the Callen-Welton theorem in the quantum case.Comment: 14 pages, 0 figures, sumitted in Physica