A modern review of the two-level approximation

Tugrul Hakioglu, Kerim Savran, Emine Meşe

Marco Frasca

The paradigm of the two-level atom is revisited and its perturbative analysis is discussed in view of the principle of duality in perturbation theory. The models we consider are a two-level atom and an ensemble of two-level atoms both interacting with a single radiation mode. The aim is to see how the latter model can be actually used as an amplifier of quantum fluctuations to the classical level through the thermodynamic limit of a very large ensemble of two-level atoms [M. Frasca, Phys. Lett. A 283, 271 (2001)]. The thermodynamic limit can be very effective in generating both classical states and decoherence on a quantum system that evolves without dissipation. Decoherence without dissipation is indeed an effect of a single two-level atom interacting with an ensemble of two-level atoms, a situation that proves to be useful to understand recent experiments on nanoscale devices showing unexpected disappearance of quantum coherence at very low temperatures.

N. V. Brazovskaya, V. E. Brazovskii

We review the validity of the several representations of the two-level approximation

Georg Junker

Franklin E. Schroeck

This conference was organized under the aegis of the University of Joensuu “to review the impact of the E.P.R. argument on the development of quantum theory, to discuss the philosophical implications of recent experimental and theoretical results on the E.P.R. problem, and to survey some other recent trends in the interpretation of quantum mechanics and classical mechanics.” There were approximately fifty lectures (and another fifty offered), two panel discussions, with over one hundred and fifty participants representing twenty five countries, which is remarkable since one physicist reviewing the original proposal for the conference termed E.P.R. as “the problem that is not a problem!”

M. Kira, S. W. Koch