1,913,012 research outputs found
Dynamic Structure Factor of Normal Fermi Gas from Collisionless to Hydrodynamic Regime
The dynamic structure factor of a normal Fermi gas is investigated by using
the moment method for the Boltzmann equation. We determine the spectral
function at finite temperatures over the full range of crossover from the
collisionless regime to the hydrodynamic regime. We find that the Brillouin
peak in the dynamic structure factor exhibits a smooth crossover from zero to
first sound as functions of temperature and interaction strength. The dynamic
structure factor obtained using the moment method also exhibits a definite
Rayleigh peak (), which is a characteristic of the hydrodynamic
regime. We compare the dynamic structure factor obtained by the moment method
with that obtained from the hydrodynamic equations.Comment: 19 pages, 9 figure
Spectral Properties of the Generalized Spin-Fermion Models
In order to account for competition and interplay of localized and itinerant
magnetic behaviour in correlated many body systems with complex spectra the
various types of spin-fermion models have been considered in the context of the
Irreducible Green's Functions (IGF) approach. Examples are generalized d-f
model and Kondo-Heisenberg model. The calculations of the quasiparticle
excitation spectra with damping for these models has been performed in the
framework of the equation- of-motion method for two-time temperature Green's
Functions within a non-perturbative approach. A unified scheme for the
construction of Generalized Mean Fields (elastic scattering corrections) and
self-energy (inelastic scattering) in terms of the Dyson equation has been
generalized in order to include the presence of the two interacting subsystems
of localized spins and itinerant electrons. A general procedure is given to
obtain the quasiparticle damping in a self-consistent way. This approach gives
the complete and compact description of quasiparticles and show the flexibility
and richness of the generalized spin-fermion model concept.Comment: 37 pages, Late
Allowed charge transfers between coherent conductors driven by a time-dependent scatterer
We derive constraints on the statistics of the charge transfer between two
conductors in the model of arbitrary time-dependent instant scattering of
non-interacting fermions at zero temperature. The constraints are formulated in
terms of analytic properties of the generating function: its zeroes must lie on
the negative real axis. This result generalizes existing studies for scattering
by a time-independent scatterer under time-dependent bias voltage.Comment: 5 pages, no figures, corrected misprints and minor changes in version
Production, Competition Indices, and Nutritive Values of Setaria Splendida, Centrosema Pubescens, and Clitoria Ternatea in Mixed Cropping Systems in Peatland
This research was conducted to evaluate production, different competition indices and nutritive value of Setaria splendida, Centrosema pubescens, and Clitoria ternatea in monoculture and mix cropping system on peat soil land. The experiment was set up in a randomized complete block design with five treatments and three replications. The five treatments were: S. splendida sole cropping (SS), C. pubescens sole cropping (CP), C. ternatea sole cropping (CT), S. splendida and C. pubescens mix cropping (SS/CP) and S. splendida/C. ternatea mix cropping (SS/CT). The DM yield of S. splendida in mixed cropping with C. pubescens increased 43.4% and in mix cropping with C. ternatea increased 15.7% compared to sole S. splendida. The value of land equivalent ratio of SS/CP (LERSS/CP) was >1. The LERSS/CT value was <1. The crowding coefficient value of S. splendida (KSS) was higher than KCP and KCT. The total value of KSS/CP and KSS/CT were >1. The competition ratio (CR) values of S. splendida in both mix cropping were >1. The agressivity (A) values of S. splendida in both mix cropping were positive. The crude protein, NDF and ADF content of forage were not affected by mix cropping system. In conclusion, mix cropping in peatland do not affect productivity and nutritive value of S. splendida, C. pubescens, and C. ternatea. S. splendida is more effective in exploiting environmental resources when intercropped with C. pubescens compared to C. ternatea on peatland
Coherent interactions between phonons and exciton or exciton-polariton condensates
We analyse the interaction of exciton and exciton-polariton condensates in
semiconductor microcavity with a coherent acoustic wave. An analytical solution
for the dispersion of excitations of coupled condensate-phonon system is found
in the approximation of k-independent interactions. Accounting for k-dependence
results in a stronger modification of the dispersion, and even in the
appearance of the "roton instability" region
Crossover from percolation to diffusion
A problem of the crossover from percolation to diffusion transport is
considered. A general scaling theory is proposed. It introduces
phenomenologically four critical exponents which are connected by two
equations. One exponent is completely new. It describes the increase of the
diffusion below percolation threshold. As an example, an exact solution of one
dimensional lattice problem is given. In this case the new exponent .Comment: 10 pages, 1 figur
configuration of the system
We study the configuration of the system by
considering as a coupled channel. We solve the Faddeev equations
for these systems and find confirmation of the existence of a new
resonance around 1920 MeV with predicted in a single-channel
potential model and also found in a Faddeev calculation as an
state, with the generated in the ,
interaction.Comment: Published versio
Schrodinger cat animated on a quantum computer
We present a quantum algorithm which allows to simulate chaos-assisted
tunneling in deep semiclassical regime on existing quantum computers. This
opens new possibilities for investigation of macroscopic quantum tunneling and
realization of semiclassical Schr\"odinger cat oscillations. Our numerical
studies determine the decoherence rate induced by noisy gates for these
oscillations and propose a suitable parameter regime for their experimental
implementation.Comment: research at Quantware MIPS Center http://www.quantware.ups-tlse.fr ;
revtex, 4 pages, 4 figure
Floquet theory of microwave absorption by an impurity in two dimensional electron gas
We investigate the dynamics of a two-dimensional electron gas (2DEG) under
circular polarized microwave radiation in presence of dilute localized
impurities. Inspired by recent developments on Floquet topological insulators
we obtain the Floquet wavefunctions of this system which allow us to predict
the microwave absorption and charge density responses of the electron gas, we
demonstrate how these properties can be understood from the underlying
semiclassical dynamics even for impurities with a size of around a magnetic
length. The charge density response takes the form of a rotating charge density
vortex around the impurity that can lead to a significant renormalization of
the external microwave field which becomes strongly inhomogeneous on the scale
of a cyclotron radius around the impurity. We show that this in-homogeneity can
suppress the circular polarization dependence which is theoretically expected
for MIRO but which was not observed in MIRO experiments on semiconducting
2DEGs. Our explanation, for this so far unexplained polarization independence,
has close similarities with the Azbel'-Kaner effect in metals where the
interaction length between the microwave field and conduction electrons is much
smaller than the cyclotron radius due to skin effect generating harmonics of
the cyclotron resonance
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