Self-Trapping of Exciton-Polariton Condensates in GaAs Microcavities

The self-trapping of exciton-polariton condensates is demonstrated and explained by the formation of a new polaronlike state. Above the polariton lasing threshold, local variation of the lattice temperature provides the mechanism for an attractive interaction between polaritons. Because of this attraction, the condensate collapses into a small bright spot. Its position and momentum variances approach the Heisenberg quantum limit. The self-trapping does not require either a resonant driving force or a presence of defects. The trapped state is stabilized by the phonon-assisted stimulated scattering of excitons into the polariton condensate. While the formation mechanism of the observed self-trapped state is similar to the Landau-Pekar polaron model, this state is populated by several thousands of quasiparticles, in a striking contrast to the conventional single-particle polaron state

Increasing of new GEO/HEO space debris discovery rate with ISON optical network

International Scientific Optical Network (ISON) represents one of largest systems specializing in observation of space objects. ISON provides permanent monitoring of the whole GEO region, regular surveying of Molniya type orbits, and tracking of objects at GEO, GTO, HEO and LEO. ISON project is continuously developing and is joining now the 37 observation facilities in 16 countries with 86 telescopes of different class (aperture from 12.5 cm to 2.6 m). 15.4 millions measurements in 2.1 millions of tracklets for about 5000 objects are collected by KIAM in 2015. 339 new space objects have been discovered, 307 previously lost objects have been rediscovered. For comparison, 160 new objects have been discovered in 2014, and 250 in 2013. 2014 was devoted to putting into operation of small survey and follow up telescopes (including new subsystem for extended GEO surveys to determine more precise orbits for conjunction analysis). This caused some decreasing of new space debris discovery rate in 2014. During 2015 and 2016 a lot of the telescopes of 40 cm – 80 cm apertures has been putted into operation. In addition, the methodology of quick identification and follow up of new space objects has been adjusted in part of ISON observatories. This resulted significant increasing of GEO/HEO space debris discovery rate. Achieved parameters of the above mentioned telescopes and obtained results will be presented and discussed. It is planned to start the printing of KIAM monthly bulletin with orbits of new discovered space debris