Artifical atoms in interacting graphene quantum dots

We describe the theory of few Coulomb-correlated electrons in a magnetic quantum dot formed in graphene. While the corresponding nonrelativistic (Schr\"odinger) problem is well understood, a naive generalization to graphene's "relativistic" (Dirac-Weyl) spectrum encounters divergencies and is ill-defined. We employ Sucher's projection formalism to overcome these problems. Exact diagonalization results for the two-electron quantum dot, i.e., the artificial helium atom in graphene, are presented.Comment: 4+ pages, 2 figure

Time-ordering Dependence of Measurements in Teleportation

We trace back the phenomenon of "delayed-choice entanglement swapping" as it was realized in a recent experiment to the commutativity of the projection operators that are involved in the corresponding measurement process. We also propose an experimental set-up which depends on the order of successive measurements corresponding to noncommutative projection operators. In this case entanglement swapping is used to teleport a quantum state from Alice to Bob, where Bob has now the possibility to examine the noncommutativity within the quantum history.Comment: 20 pages, 7 figures; v2; formalism of isometries elaborately discussed, some changes in formulas, figure and reference added; typos correcte

High dispersive and monolithic 100% efficiency grisms

We present a type of grism, a series combination of transmission grating and prism, in which we reduce the number of diffraction orders and achieve a configuration with very high angular dispersion. The grism can be fabricated from a single dielectric material and requires no metallic or dielectric film layers for high transmission diffraction efficiency. One can reach 100% in the -1st transmission diffraction order and the equal damage threshold as the dielectric bulk material. We realized such an element in fused silica with an efficiency of more then 99%. The bevel backside reflection is reduced by a statistical antireflective structure, so we measured an efficiency of the entire grism of 95% at a single wavelength

Residual entanglement of accelerated fermions is not nonlocal

We analyze the operational meaning of the residual entanglement in non-inertial fermionic systems in terms of the achievable violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality. We demonstrate that the quantum correlations of fermions, which were previously found to survive in the infinite acceleration limit, cannot be considered to be non-local. The entanglement shared by an inertial and an accelerated observer cannot be utilized for the violation of the CHSH inequality in case of high accelerations. Our results are shown to extend beyond the single mode approximation commonly used in the literature.Comment: 5 pages, 3 figures; v2: minor changes, reference and section headers adde