The possibility of creating a Bose condensate of trapped atoms in a non-ground state is suggested. Such a nonequilibrium Bose condensate can be formed if one, first, obtains the conventional Bose condensate in the ground state and then transfers the condensed atoms to a non-ground state by means of a resonance pumping. The properties of ground and non-ground states are compared and plausible applications of such nonequilibrium condensates are discussed. 03.75.Fi

The state of art in studying thermodynamic properties of hot and dense nuclear matter is reviewed with the special emphasis on the confinement-deconfinement transition between hadron matter and quark-gluon plasma. The most popular models used for describing deconfinement are analysed, including statistical bootstrap models, pure phase models, the model of clustered quarks, and the string-flip potential model. Predictions of these models are compared with the lattice numerical simulations. It is concluded that precursor fluctuation effects must be taken into account in order to get a realistic description of deconfinement transition. The existence of precursor fluctuations is in line with the dynamical confinement scenario and suggests that deconfinement cannot be considered as a transition between pure hadron and quark-gluon phases. All this supports the concept of cluster coexistence advocated by the authors of this review: Quark-gluon plasma and hadron clusters are different quantum states of the same system, so that any statistical model pretending to treat nuclear matter under extreme conditions must incorporate into itself the probability of these different channels. The ways of constructing statistical models with plasma-cluster coexistence are discussed and thermodynamic properties of such models are analysed.

Atomic squeezing is studied for the case of large systems of radiating atoms, when collective effects are well developed. All temporal stages are analyzed, starting with the quantum stage of spontaneous emission, passing through the coherent stage of superradiant emission, and going to the relaxation stage ending with stationary solutions. A method of governing the temporal behaviour of the squeezing factor is suggested. The influence of a squeezed effective vacuum on the characteristics of collective emission is also investigated.