10,903 research outputs found
A simple deterministic self-organized critical system
We introduce a new continuous cellular automaton that presents self-organized
criticality. It is one-dimensional, totally deterministic, without any kind of
embedded randomness, not even in the initial conditions. This system is in the
same universality class as the Oslo rice pile system, boundary driven interface
depinning and the train model for earthquakes. Although the system is chaotic,
in the thermodynamic limit chaos occurs only in a microscopic level.Comment: System slightly modified. New results on Liapunov exponents.
Submitted for publication (8 pages
Electron Fabry-Perot interferometer with two entangled magnetic impurities
We consider a one-dimensional (1D) wire along which single conduction
electrons can propagate in the presence of two spin-1/2 magnetic impurities.
The electron may be scattered by each impurity via a contact-exchange
interaction and thus a spin-flip generally occurs at each scattering event.
Adopting a quantum waveguide theory approach, we derive the stationary states
of the system at all orders in the electron-impurity exchange coupling
constant. This allows us to investigate electron transmission for arbitrary
initial states of the two impurity spins. We show that for suitable electron
wave vectors, the triplet and singlet maximally entangled spin states of the
impurities can respectively largely inhibit the electron transport or make the
wire completely transparent for any electron spin state. In the latter case, a
resonance condition can always be found, representing an anomalous behaviour
compared to typical decoherence induced by magnetic impurities. We provide an
explanation for these phenomena in terms of the Hamiltonian symmetries.
Finally, a scheme to generate maximally entangled spin states of the two
impurities via electron scattering is proposed.Comment: 19 page
Chaos in black holes surrounded by gravitational waves
The occurrence of chaos for test particles moving around Schwarzschild black
holes perturbed by a special class of gravitational waves is studied in the
context of the Melnikov method. The explicit integration of the equations of
motion for the homoclinic orbit is used to reduce the application of this
method to the study of simple graphics.Comment: 15 pages, LaTex
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