Empirical versus exact numerical quasilinear analysis of electromagnetic instabilities driven by temperature anisotropy

In the present paper, quasilinear development of anisotropy-driven electromagnetic instabilities is computed on the basis of recently formulated empirical wave dispersion relation and compared against exact numerical calculation based upon transcendental plasma dispersion function and exact numerical roots. Upon comparison with the exact method it is demonstrated that the empirical model provides reasonable results. The present findings may be relevant to space physical application, as the present paper provides a useful short-cut research method for self-consistent analysis of temporal development of anisotropy-driven instabilities.

Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down Conversion

The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons.

Relationship Between Spatial Coherence of Synchrotron Radiation and Emittance

Analytical calculation of the first-order spatial coherence for the Gaussian beam and the exact numerical calculation for synchrotron radiation are compared in this paper. The approximation of regarding synchrotron radiation as a Gaussian beam is often used to investigate the brightness, the flux and some qualitative properties. Calculations show that synchrotron radiation does not have as high coherence as the Gaussian beam because of the beam profile, the phases of the wave and the polarization. If one can measure the beam size and the spatial coherence of synchrotron radiation, it is possible to determine the total photon beam emittance without any knowledge of the Twiss parameters of the ring.

NON-ADIABATIC TRANSPORT IN QUANTUM POINT CONTACTS

We have performed an exact numerical calculation on the conductance of a narrow constriction in a two-dimensional electron gas and discovered a novel sum rule that the conductance is invariant with respect to the channel mixing. This feature explains why the adiabatic approximation results fit the experimental data quantitatively. A similar sum rule has been found for the excess noise. These important conclusions remain to be derived analytically.