All-optical photon echo and memory on a chip

We demonstrate that a photon echo can be implemented by all-optical means using an array of on-chip high-finesse ring cavities whose parameters are chirped in such a way as to support equidistant spectra of cavity modes. When launched into such a system, a classical or quantum optical signal -- even a single-photon field -- becomes distributed between individual cavities, giving rise to prominent coherence echo revivals at well-defined delay times, controlled by the chirp of cavity parameters. This effect enables long storage times for high-throughput broadband optical delay and quantum memory.Comment: 7 pages, 5 figure

Kinematically detected polar rings/disks in blue compact dwarf galaxies

Polar ring galaxies are systems with nearly orthogonally rotated components. We have found the gas on polar (or strongly inclined) orbits in two BCD galaxies using ionized gas velocity fields taken with a Fabry-Perot interferometer of the SAO RAS 6-m telescope. Our analysis shows that all ionized gas in Mrk 33 is concentrated in a compact disk (3 kpc in diameter) which rotates in the polar plane relative to the main stellar body. The gaseous disk in Mrk 370 has a more complex structure with a heavily warped innermost part. The presence of polar gaseous structures supports an idea that current the burst of star formation in these galaxies is due to the external gas accretion or merging. A possible fraction of polar structures among BCD galaxies seems to be very large (up to 10-15%)Comment: to appear in the proceedings of the conference "A Universe of dwarf galaxies" (Lyon, June 14-18, 2010