601 research outputs found
Anticipated synchronization and the predict-prevent control method in the FitzHugh-Nagumo model system
We study the synchronization region of two unidirectionally coupled, in a
master-slave configuration, FitzHugh-Nagumo systems under the influence of
external forcing terms. We observe that anticipated synchronization is robust
to the different types of forcings. We then use the predict-prevent control
method to suppress unwanted pulses in the master system by using the
information of the slave output. We find that this method is more efficient
than the direct control method based on the master. Finally, we observe that a
perfect matching between the parameters of the master and the slave is not
necessary for the control to be efficient. Moreover, this parameter mismatch
can, in some cases, improve the control
Dipolar condensates confined in a toroidal trap: ground state and vortices
We study a Bose-Einstein condensate of 52Cr atoms confined in a toroidal trap
with a variable strength of s-wave contact interactions. We analyze the effects
of the anisotropic nature of the dipolar interaction by considering the
magnetization axis to be perpendicular to the trap symmetry axis. In the
absence of a central repulsive barrier, when the trap is purely harmonic, the
effect of reducing the scattering length is a tuning of the geometry of the
system: from a pancake-shaped condensate when it is large, to a cigar-shaped
condensate for small scattering lengths. For a condensate in a toroidal trap,
the interaction in combination with the central repulsive Gaussian barrier
produces an azimuthal dependence of the particle density for a fixed radial
distance. We find that along the magnetization direction the density decreases
as the scattering length is reduced but presents two symmetric density peaks in
the perpendicular axis. For even lower values of the scattering length we
observe that the system undergoes a dipolar-induced symmetry breaking
phenomenon. The whole density becomes concentrated in one of the peaks,
resembling an origin-displaced cigar-shaped condensate. In this context we also
analyze stationary vortex states and their associated velocity field, finding
that this latter also shows a strong azimuthal dependence for small scattering
lengths. The expectation value of the angular momentum along the z direction
provides a qualitative measure of the difference between the velocity in the
different density peaks.Comment: 9 pages, 12 figure
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