580 research outputs found
Bistability and Hysteresis of Intersubband Absorption in Strongly Interacting Electrons on Liquid Helium
We study nonlinear inter-subband microwave absorption of electrons bound to
the liquid helium surface. Already for a comparatively low radiation intensity,
resonant absorption due to transitions between the two lowest subbands is
accompanied by electron overheating. The overheating results in a significant
population of higher subbands. The Coulomb interaction between electrons causes
a shift of the resonant frequency, which depends on the population of the
excited states and thus on the electron temperature . The latter is
determined experimentally from the electron photoconductivity. The
experimentally established relationship between the frequency shift and
is in reasonable agreement with the theory. The dependence of the shift on the
radiation intensity introduces nonlinearity into the rate of the inter-subband
absorption resulting in bistability and hysteresis of the resonant response.
The hysteresis of the response explains the behavior in the regime of frequency
modulation, which we observe for electrons on liquid He and which was
previously seen for electrons on liquid He
Simulation of observed climate changes in 1850–2014 with climate model INM-CM5
Climate changes observed in 1850–2014 are modeled and studied on the basis
of seven historical runs with the climate model INM-CM5 under the scenario
proposed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). In
all runs global mean surface temperature rises by 0.8 K at the end of the
experiment (2014) in agreement with the observations. Periods of fast warming
in 1920–1940 and 1980–2000 as well as its slowdown in 1950–1975 and
2000–2014 are correctly reproduced by the ensemble mean. The notable change
here with respect to the CMIP5 results is the correct reproduction of the
slowdown in global warming in 2000–2014 that we attribute to a change in
ocean heat uptake and a more accurate description of the total solar
irradiance in the CMIP6 protocol. The model is able to reproduce the correct
behavior of global mean temperature in 1980–2014 despite incorrect phases of
the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation indices
in the majority of experiments. The Arctic sea ice loss in recent decades is
reasonably close to the observations in just one model run; the model
underestimates Arctic sea ice loss by a factor of 2.5. The spatial pattern of
the model mean surface temperature trend during the last 30 years looks close
to the one for the ERA-Interim reanalysis. The model correctly estimates the
magnitude of stratospheric cooling.</p
Climate variations in the Northern Hemisphere based on the use of an atmosphere-ocean IPCC model
Forced and natural variability of modelled and observed Atlantic Ocean temperature and Atlantic Meridional Overturning Circulation (AMOC) is studied. In the observations and in a forced climate model run, we find increasing temperature at 1000m in the Atlantic (20N). SVD analysis shows that, for both model data and observations, a high index of North Atlantic Oscillation (NAO) corresponds
to negative temperature anomaly at 1000m to the north of 55N, although geographical details of temperature anomaly distribution are different for the model and observations. Particular attention has been paid to the influence of the fresh water flux due to the present global warning on the slowing down of the AMOC. It is shown that fresh water flux change is only a secondary cause of reduced AMOC in global warming conditions, while heat flux change is probably the main reason. Finally, it is shown that internal model AMOC variability is positively correlated with the near-surface air temperature in Atlantic-European Arctic sector on a
10-year time scale
Effects of kinked linear defects on planar flux line arrays
In the hard core limit, interacting vortices in planar type II
superconductors can be modeled as non-interacting one dimensional fermions
propagating in imaginary time. We use this analogy to derive analytical
expressions for the probability density and imaginary current of vortex lines
interacting with an isolated bent line defect and to understand the pinning
properties of such systems. When there is an abrupt change of the direction of
the pinning defect, we find a sinusoidal modulation of the vortex density in
directions both parallel and perpendicular to the defect.Comment: 13 figure
Amplification of Fluctuations in Unstable Systems with Disorder
We study the early-stage kinetics of thermodynamically unstable systems with
quenched disorder. We show analytically that the growth of initial fluctuations
is amplified by the presence of disorder. This is confirmed by numerical
simulations of morphological phase separation (MPS) in thin liquid films and
spinodal decomposition (SD) in binary mixtures. We also discuss the
experimental implications of our results.Comment: 15 pages, 4 figure
Magnetic resonance force microscopy of individual domain wall
The sample preparation and micromagnetic simulations were supported by Russian Science Foundation (project # 16-12-10254)
The effect of the probe magnetic moment orientation of magnetic resonance force microscope on the spectra of spin wave resonances
This work was supported by the Russian Science Foundation (project 16-12-10254)
Electric field induced strong localization of electrons on solid hydrogen surface: possible applications to quantum computing
Two-dimensional electron system on the liquid helium surface is one of the
leading candidates for constructing large analog quantum computers (P.M.
Platzman and M.I. Dykman, Science 284, 1967 (1999)). Similar electron systems
on the surfaces of solid hydrogen or solid neon may have some important
advantages with respect to electrons on liquid helium in quantum computing
applications, such as larger state separation , absence of
propagating capillary waves (or ripplons), smaller vapor pressure, etc. As a
result, it may operate at higher temperatures. Surface roughness is the main
hurdle to overcome in building a realistic quantum computer using these states.
Electric field induced strong localization of surface electrons is shown to be
a convenient tool to characterize surface roughness.Comment: 4 pages, 3 figure
An application of the Ryll-Nardzewski-Woyczyński theorem to a uniform weak law for tail series of weighted sums of random elements in Banach spaces
For a sequence of Banach space valued random elements {Vn,n≥1} (which are not necessarily independent) with the series ∑n=1 ∞Vn converging unconditionally in probability and an infinite array a={ani,i≥n,n≥1} of constants, conditions are given under which (i) for all n≥1, the sequence of weighted sums ∑i=n maniVi converges in probability to a random element Tn(a) as m→∞, and (ii) Tn(a)→P0 uniformly in a as n→∞ where a is in a suitably restricted class of infinite arrays. The key tool used in the proof is a theorem of Ryll-Nardzewski and Woyczyński (1975, Proc. Amer. Math. Soc. 53, 96-98). © 2000 Elsevier Science B.V
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