455 research outputs found
Minimizing the linewidth of the Flux-Flow Oscillator
For the first time the linewidth of Flux-Flow Oscillator has been calculated
by direct computer simulation of the sine-Gordon equation with noise. Nearly
perfect agreement of the numerical results with the formula derived in [Phys.
Rev. B, {\bf 65}, 054504 (2002)] has been achieved. It has been demonstrated
that for homogeneous bias current distribution the linewidth actually does not
depend on the junction length for practically interesting parameters range.
Depending on the length of the unbiased tail, the power may be maximized and
the linewidth may be minimized in a broad range of bias currents. The linewidth
can be decreased further by 1.5 times by proper load matching.Comment: 4 pages, 6 figure
Suppression of timing errors in short overdamped Josephson junctions
The influence of fluctuations and periodical driving on temporal
characteristics of short overdamped Josephson junction is analyzed. We obtain
the standard deviation of the switching time in the presence of a dichotomous
driving force for arbitrary noise intensity and in the frequency range of
practical interest. For sinusoidal driving the resonant activation effect has
been observed. The mean switching time and its standard deviation have a
minimum as a function of driving frequency. As a consequence the optimization
of the system for fast operation will simultaneously lead to minimization of
timing errors.Comment: 4 pages, 4 figures, in press in Physical Review Letter
Γ-convergence and homogenization of functionals in Sobolev spaces with variable exponents
AbstractThis paper is devoted to homogenization and minimization problems for variational functionals in the framework of Sobolev spaces with continuous variable exponents. We assume that the sequence of exponents converges in the uniform metric and that the Lagrangian has a periodic microstructure. Then under natural coerciveness assumptions we prove a Γ-convergence result and, as a consequence, the convergence of minimizers (solutions to the corresponding Euler equations)
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