The Fifth Seminar on Quantum Optics was held in Minsk from May 30 to June 1, 1994. A renewed interest in the paradox of negative feedback associated with new experimental results made by A. V. Masalov and the utilization of the theory of continuous quantum measurements in the description of feedback (S.Ya. Kilin, D.B. Horoshko, and L. Plimak) was evident. The diversity of approaches and incompleteness of the discussion in scientific literature currently leave this question open for discussion. A.V. Masalov, M.V. Vasilev, A.S. Troshin, and D.B. Horoshko made reports concerning this question at the seminar.
The presentation of the reports "Quantum Optics of Single Atoms under Mono- and Bichromatic Excitation" (S.Ya. Kilin, T.B. Krinitskaya, A.P. Nizovtsev, and D.S. Mogilevtsev), "Intracavity Quantum States of a Macromaser and the Possibility of Their Observation" (Yu.M. Golubev), and "Three-Dimensional Theory of a Zeeman Trap" (J. Mostovski, ITP, Warsaw) reflected the movement in interest in the field of quantum optics towards intracavity quantum interactions, making it possible to realize the regime of "strong" atom-field interaction, when the constant of this interaction exceeds the decay rate of the field in a cavity and the rate of spontaneous decay of an atom.
Reduction of the noise level of a quantum-dimensional semiconductor laser was reported by A.S. Trifonov (A.F. Ioffe Institute of Physics and Technology, Russian Academy of Sciences).
New results on the observation of squeezed vibrational states in molecules were discussed in the report by A. V. Vinogradov. Generation of superposition states of "Schroedinger cat" type in four-wave interaction was the subject of the report by D.S. Mogilevtsev. The reports by A.S. Chirkin, A.A. Orlov, and N.V. Korolkova (MSU) were devoted to the questions of polarization-squeezed light whose discussion originated at SQO-IV.
Nonlinear and parametric interactions of quantum optical fields remained the focus of attention of the participants of the seminar (I.V. Sokolov, Ya.A. Fofanov, V.N. Gorbachev, A.I. Trubilko, I.M. Sokolov, T.M. Maevskaya, V.N. Beskrovnyi, A. Stabinis, and A. Berzanskis).
E.D. Trifonov presented a highly interesting report at the seminar. It dealt with the phenomenon of synchronization of superfluorescence pulses in reflection from the boundaries of an active layer. The reports by R.G. Zaporozhchenko and V.A. Orlovich et al., on further studies of special features of macroscopic fluctuations in SRS were also presented at the seminar.
The seminar on Quantum Optics was held in times that were not the best for the development of science. The political and historical events that served as the background for this series of seminars (Chernobyl disaster and the disintegration of the USSR, for example) affected scientific research on the territory of the former USSR. However, the fact that we get together at this seminar once every two years, due to the activity of the organizers and, what is most important, young participants, gives reason to hope that the seminar will continue fulfill its function.