24,646 research outputs found
Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction
We have studied the analytical dynamics of Bell nonlocality as measured by
CHSH inequality and entanglement as measured by concurrence for two noisy
qubits that have dipole-dipole interaction. The nonlocal entanglement created
by the dipole-dipole interaction is found to be protected from sudden death for
certain initial states
Quantum Electrodynamics and the Origins of the Exchange, Dipole-Dipole, and Dzyaloshinsky-Moriya Interactions in Itinerant Fermion Systems
It is shown how the exchange interaction, the dipole-dipole interaction, and
the Dzyaloshinsky-Moriya interaction between electronic spin-density
fluctuations emerge naturally from a field-theoretic framework that couples
electrons to the fluctuating electromagnetic potential. Semi-quantitative
estimates are given to determine when the dipole-dipole interaction, which is
often neglected, needs to be considered, and various applications are
discussed, with an emphasis on weak ferromagnets and on helimagnets.Comment: 12pp, 3 fig
Simplified approach to double jumps for fluorescing dipole-dipole interacting atoms
A simplified scheme for the investigation of cooperative effects in the
quantum jump statistics of small numbers of fluorescing atoms and ions in a
trap is presented. It allows the analytic treatment of three dipole-dipole
interacting four-level systems which model the relevant level scheme of Ba+
ions. For the latter, a huge rate of double and triple jumps was reported in a
former experiment and the huge rate was attributed to the dipole-dipole
interaction. Our theoretical results show that the effect of the dipole-dipole
interaction on these rates is at most 5% and that for the parameter values of
the experiment there is practically no effect. Consequently it seems that the
dipole-dipole interaction can be ruled out as a possible explanation for the
huge rates reported in the experiment.Comment: 7 pages, 6 figures, typos corrected, to appear in EPJ D (as highlight
paper
Ferromagnetic Resonance in Spinor Dipolar Bose--Einstein Condensates
We used the Gross--Pitaevskii equations to investigate ferromagnetic
resonance in spin-1 Bose--Einstein condensates with a magnetic dipole-dipole
interaction. By introducing the dipole interaction, we obtained equations
similar to the Kittel equations used to represent ferromagnetic resonance in
condensed matter physics. These equations indicated that the ferromagnetic
resonance originated from dipolar interaction, and that the resonance frequency
depended upon the shape of the condensate. Furthermore, spin currents driven by
spin diffusions are characteristic of this system.Comment: 8 pages, 10 figure
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