2,920 research outputs found
Photon echo quantum memory with complete use of natural inhomogeneous broadening
The photon echo quantum memory is based on a controlled rephasing of the
atomic coherence excited by signal light field in the inhomogeneously broadened
resonant line. Here, we propose a novel active mechanism of the atomic
rephasing which provides a perfect retrieval of the stored light field in the
photon echo quantum memory for arbitrary initial inhomogeneous broadening of
the resonant line. It is shown that the rephasing mechanism can exploit all
resonant atoms which maximally increases an optical depth of the resonant
transition that is one of the critical parameters for realization of highly
efficient quantum memory. We also demonstrate that the rephasing mechanism can
be used for various realizations of the photon echo quantum memory that opens a
wide road for its practical realization.Comment: 6 pages, 4 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
A synchrotron superbubble in the IC 10 Galaxy: a hypernova remnant?
The nature of the synchrotron superbubble in the IC 10 galaxy is discussed
using the results of our investigation of its ionized gas structure,
kinematics, and emission spectrum from observations made with the 6-m telescope
of the Special Astrophysical Observatory of the Russian Academy of Sciences,
and based on our analysis of the radio emission of the region. The hypernova
explosion is shown to be a more plausible mechanism of the formation of the
synchrotron superbubble compared with the earlier proposed model of multiple
supernova explosions. A compact remnant of this hypernova may be identified
with the well known X-ray binary X-1 -- an accreting black hole.Comment: 4 pages, 3 EPS figures, Accepted to MNRAS (in Letters
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