21,003 research outputs found
Solid State Analog for He-McKellar-Wilkens Quantum Phase
In this letter we investigate the quantum dynamics of a quasiparticle in the
presence of a charged screw dislocation submitted to a uniform magnetic field.
Analysing the quantum scattering for this quasiparticle we observed the
appearance of a topological quantum phase in the solution and demonstrate that
this phenomenon is the solid state analog of the He-McKeller-Wilkens effect.Comment: 7 pages, epl styl
Geometric phases in open systems: an exact model to study how they are corrected by decoherence
We calculate the geometric phase for an open system (spin-boson model) which
interacts with an environment (ohmic or nonohmic) at arbitrary temperature.
However there have been many assumptions about the time scale at which the
geometric phase can be measured, there has been no reported observation yet for
mixed states under nonunitary evolution. We study not only how they are
corrected by the presence of the different type of environments but also
estimate the corresponding times at which decoherence becomes effective. These
estimations should be taken into account when planning experimental setups to
study the geometric phase in the nonunitary regime, particularly important for
the application of fault-tolerant quantum computation.Comment: Revtex 4, 5 pages, one eps figure. Version Publishe
On the rise and fall of networked societies
We review recent results on the dynamics of social networks which suggest
that the interplay between the network formation process and volatility may
lead to the occurrence of discontinuous phase transitions and phase coexistence
in a large class of models. We then investigate the effects of negative links
-- links inhibiting local growth of the network -- and of a geographical
distribution of the agents in such models. We show, by extensive numerical
simulations, that both effects enhance this phenomenology, i.e. it increases
the size of the coexistence region.Comment: 6 pages, 4 figures, Proceedings of Granada Workshop 200
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