Realistic teleportation with linear optical elements

We calculate the highest possible information gain in a measurement of entangled states when employing a beamsplitter. The result is used to evaluate the fidelity, averaged over all unknown inputs, in a realistic teleportation protocol that takes account of the imperfect detection of Bell states. Finally, we introduce a probabilistic teleportation scheme, where measurements are made in a partially entangled basis.Comment: 3 pages + 3 figures (fig. with better resolution available from authors

Teleportation with indistinguishable particles

We analyze in a critical way the mathematical treatment of a quantum teleportation experiment performed with photon particles, showing that a symmetrization operation over both the polarization and spatial degrees of freedom of all the particles involved is necessary in order to reproduce correctly the observed experimental data.Comment: 8 pages, Latex, submitted to Phys. Lett.

Ion and mixed conducting oxides as catalysts

This paper gives a survey of the catalytic properties of solid oxides which display oxygen ion or mixed (i.e. ionic + electronic) conductivity. Particular consideration is given to the oxidation-reduction reactions of gas phase components, but attention is also devoted to oxygen exchange between gas and oxide. An attempt has been made to relate and explain the observed phenomena such as catalytic activity and selectivity in terms of the electrical conducting properties of the oxides, which depend on their crystal and defect structures.\ud \ud In a number of cases possible applications of these materials in (electro)catalytic reactors, sensors, fuel cells, oxygen pumps, etc. are indicated

Coherent quantum measurement for the direct determination of the degree of polarization and Polarization Mode Dispersion compensation

An example of a coherent measurement for the direct evaluation of the degree of polarization of a single-mode optical beam is presented. It is applied to the case of great practical importance where depolarization is caused by polarization mode dispersion. It is demonstrated that coherent measurement has the potential of significantly increasing the information gain, compared to standard incoherent measurements.Comment: 4 pages + 3 figure

Non-linear photonic crystals as a source of entangled photons

Non-linear photonic crystals can be used to provide phase-matching for frequency conversion in optically isotropic materials. The phase-matching mechanism proposed here is a combination of form birefringence and phase velocity dispersion in a periodic structure. Since the phase-matching relies on the geometry of the photonic crystal, it becomes possible to use highly non-linear materials. This is illustrated considering a one-dimensional periodic Al$_{0.4}$Ga$_{0.6}$As / air structure for the generation of 1.5 $\mu$m light. We show that phase-matching conditions used in schemes to create entangled photon pairs can be achieved in photonic crystals.Comment: 4 pages, 3 figure

Importance of the surface exchange kinetics as rate limiting step in oxygen permeation through mixed-conducting oxides

Attention is drawn to the possible involvement of the surface exchange kinetics in limiting the rate of oxygen permeation through mixed-conducting oxide ceramics. A theoretical approach is provided with which it is possible to distinguish between surface exchange- and bulk diffusion controlled kinetics of oxygen permeation. New results on the oxygen permeability of perovskites La0.8Sr0.2CoO3−σ and SrCo0.8Fe0.2O3−σ are presented. The importance of the exchange reaction re to diffusion in limiting overall oxygen transport through (La,Sr)(Co,Fe)O3−σ perovskite-type oxides is emphasized.\u