1,421 research outputs found
Edge Channel Interference Controlled by Landau Level Filling
We study the visibility of Aharonov-Bohm interference in an electronic
Mach-Zehnder interferometer (MZI) in the integer quantum Hall regime. The
visibility is controlled by the filling factor and is observed only
between and 1.0, with an unexpected maximum near .
Three energy scales extracted from the temperature and voltage dependences of
the visibility change in a very similar way with the filling factor, indicating
that the different aspects of the interference depend sensitively on the local
structure of the compressible and incompressible strips forming the quantum
Hall edge channels.Comment: 5 pages, 5 figures, final version accepted for publication in Phys.
Rev.
Search for Spatial Structures at Scales Z~1. III. The Effect of Lensing on QSO ?
We carried out a search for peak inhomogeneities in the distribution of
matter - namely clumps and voids, within the range Z ~ 1-3. We used a new
method, based on the lensing of quasars by a combination of lenses, belonging
to the above sought inhomogeneities in the matter distribution. This work
confirms the evidence of the existence of inhomogeneities found by us earlier -
of a clump (superattractor N.1), and of a void (supervoid). Besides, the
existence of a new gigantic clump (superattractor N.2) was also discovered at Z
~ 3. These clumps could well serve as centers of the Bose-condensation in the
early Universe; in particular - as Anselm's arion condensate, which leads to
the formation of quasiperiodic structures with a period p ~ 100-200 Mpc.Comment: 22 pages, 2 figures, 6 tables. submitted to Astrophys.& Space Sc
AUTOPARAMETRIC STABILIZER OF OSCILLATION AMPLITUDE
A method of automatic maintenance of vibration amplitude of a number of mechanisms at given level, when exiting force amplitude is varied greatly is given. For this purpose a pendulum is attached to a mechanism through a viscoelastic hinge. Load of a pendulum can move along an arm and it is viscoelastic connected to it
Controllable beam shaping of coherent and incoherent beams by a laser amplifier
We propose the technique for a controllable manipulation of the transverse intensity distribution of an output beam by the temporal adjustment of a transverse gain profile in a laser amplifier. It was created by an independent manipulation of the output powers of each of the two pump diodes. The output beam of the laser amplifier is able to vary both the output power and the transverse intensity distribution. Additionally, it was shown experimentally that this technique is valid for the case of incoherent laser beam shaping
Ion composition measurements and modelling at altitudes from 140 to 350 km using EISCAT measurements
International audienceThis work aims at processing the data of CP1 and CP2 programs of EISCAT ionospheric radar from 1987 to 1994 using the "full profile" method which allows to solve the "temperature-composition" ambiguity problem in the lower F region. The program of data analysis was developed in the CEPHAG in 1995–1996. To improve this program, we implemented another analytical function to model the ion composition profile. This new function better reflects the real profile of the composition. Secondly, we chose the best method to select the initial conditions for the "full profile" procedure. A statistical analysis of the results was made to obtain the averages of various parameters: electron concentration and temperature, ion temperature, composition and bulk velocity. The aim is to obtain models of the parameter behaviour defining the ion composition profiles : z50 (transition altitude between atomic and molecular ions) and dz (width of the profile), for various seasons and for high and low solar activities. These models are then compared to other models. To explain the principal features of parameters z50 and dz, we made an analysis of the processes leading to composition changes and related them to production and electron density profile. A new experimental model of ion composition is now available
Counting Statistics and Dephasing Transition in an Electronic Mach-Zehnder Interferometer
It was recently suggested that a novel type of phase transition may occur in
the visibility of electronic Mach-Zehnder Interferometers. Here, we present
experimental evidence for the existence of this transition. The transition is
induced by strongly non-Gaussian noise that originates from the strong coupling
of a quantum point contact to the interferometer. We provide a transparent
physical picture of the effect, by exploiting a close analogy to the
neutrino-oscillations of particle physics. In addition, our experiment
constitutes a probe of the singularity of the elusive full counting statistics
of a quantum point contact.Comment: 7 pages, 4 figures (+Supplement 8 pages, 9 figures
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