Title: Fluctuations in quantum devices
Authors: H.Haken (Institute for Theoretical Physics, Center of Synergetics, University of Stuttgart, Pfaffenwaldring 57/4, D-70550 Stuttgart, Germany)

Logical gates can be formalized by Boolean algebra whose elementary operations can be realized by devices that employ the interactions of macroscopic numbers of elementary excitations such as electrons, holes, photons etc. With increasing miniaturization to the nano scale and below, quantum fluctuations become important and can no longer be ignored. Based on Heisenberg equations of motion for the creation and annihilation operators of elementary excitations, I determine the noise sources of composite quantum systems.

Key words: quantum fluctuations, elementary excitations, Heisenberg equations of motion, logical devices, noise in composite quantum systems
PACS: 05.40.-a, 05.30.-d