3,420 research outputs found
Coulomb drag at zero temperature
We show that the Coulomb drag effect exhibits saturation at small
temperatures, when calculated to the third order in the interlayer
interactions. The zero-temperature transresistance is inversely proportional to
the third power of the dimensionless sheet conductance. The effect is therefore
the strongest in low mobility samples. This behavior should be contrasted with
the conventional (second order) prediction that the transresistance scales as a
certain power of temperature and is almost mobility-independent. The result
demonstrates that the zero-temperature drag is not an unambiguous signature of
a strongly-coupled state in double-layer systems.Comment: 4 pages, 2 figure
Frequency dispersion of photon-assisted shot noise in mesoscopic conductors
We calculate the low-frequency current noise for AC biased mesoscopic chaotic
cavities and diffusive wires. Contrary to what happens for the admittance, the
frequency dispersion is not dominated by the electric response time (the "RC"
time of the circuit), but by the time that electrons need to diffuse through
the structure (dwell time or diffusion time). Frequency dispersion of noise
stems from fluctuations of the Fermi distribution function that preserve charge
neutrality. Our predictions can be verified with present experimental
technology.Comment: 5 pages, 3 Figure
Nonequilibrium kinetics of a disordered Luttinger liquid
We develop a kinetic theory for strongly correlated disordered
one-dimensional electron systems out of equilibrium, within the Luttinger
liquid model. In the absence of inhomogeneities, the model exhibits no
relaxation to equilibrium. We derive kinetic equations for electron and plasmon
distribution functions in the presence of impurities and calculate the
equilibration rate . Remarkably, for not too low temperature and bias
voltage, is given by the elastic backscattering rate, independent of
the strength of electron-electron interaction, temperature, and bias.Comment: 4 pages, 3 figures, revised versio
Wigner-Dyson Statistics from the Keldysh Sigma-Model
The level statistics of disordered metallic grains with broken time reversal
invariance is obtained from a saddle point analysis of the Keldysh nonlinear
sigma-model
Dynamics of excitations in a one-dimensional Bose liquid
We show that the dynamic structure factor of a one-dimensional Bose liquid
has a power-law singularity defining the main mode of collective excitations.
Using the Lieb-Liniger model, we evaluate the corresponding exponent as a
function of the wave vector and the interaction strength
Extinction in Lotka-Volterra model
Competitive birth-death processes often exhibit an oscillatory behavior. We
investigate a particular case where the oscillation cycles are marginally
stable on the mean-field level. An iconic example of such a system is the
Lotka-Volterra model of predator-prey competition. Fluctuation effects due to
discreteness of the populations destroy the mean-field stability and eventually
drive the system toward extinction of one or both species. We show that the
corresponding extinction time scales as a certain power-law of the population
sizes. This behavior should be contrasted with the extinction of models stable
in the mean-field approximation. In the latter case the extinction time scales
exponentially with size.Comment: 11 pages, 17 figure
Replica treatment of non-Hermitian disordered Hamiltonians
We employ the fermionic and bosonic replicated nonlinear sigma models to
treat Ginibre unitary, symplectic, and orthogonal ensembles of non-Hermitian
random matrix Hamiltonians. Using saddle point approach combined with Borel
resummation procedure we derive the exact large-N results for microscopic
density of states in all three ensembles. We also obtain tails of the density
of states as well the two-point function for the unitary ensemble.Comment: REVTeX 3.1, 13 pages, 1 figure; typos fixed (v2
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