Properties of low temperature quantum noise

R. Jung, G.-L. Ingold, P. Schramm, and H. Grabert

in: Noise in Physical Systems and 1/f Noise—1985, ed. by A. D'Amico and P. Mazzetti, pp. 277–279 (Elsevier, 1986)

The nature of the noise described by the c-number quantum Langevin equation is investigated. Subtleties in the stochastic calculus are shown to originate from the differences between quantum noise and classical noise. For a harmonically bound particle the zero temperature correlation functions are shown to display long time tails. At finite temperatures an algebraic decay at intermediate times is followed by an exponential decay with time constant τ = ℏ/2πkBT. Some general conclusions for nonlinear sytems are drawn.