A note on the integrability of non-Hermitian extensions of Calogero-Moser-Sutherland models

We consider non-Hermitian but PT-symmetric extensions of Calogero models, which have been proposed by Basu-Mallick and Kundu for two types of Lie algebras. We address the question of whether these extensions are meaningful for all remaining Lie algebras (Coxeter groups) and if in addition one may extend the models beyond the rational case to trigonometric, hyperbolic and elliptic models. We find that all these new models remain integrable, albeit for the non-rational potentials one requires additional terms in the extension in order to compensate for the breaking of integrability.Comment: 10 pages, Late

Influence of branch points in the complex plane on the transmission through double quantum dots

We consider single-channel transmission through a double quantum dot system consisting of two single dots that are connected by a wire and coupled each to one lead. The system is described in the framework of the S-matrix theory by using the effective Hamiltonian of the open quantum system. It consists of the Hamiltonian of the closed system (without attached leads) and a term that accounts for the coupling of the states via the continuum of propagating modes in the leads. This model allows to study the physical meaning of branch points in the complex plane. They are points of coalesced eigenvalues and separate the two scenarios with avoided level crossings and without any crossings in the complex plane. They influence strongly the features of transmission through double quantum dots.Comment: 30 pages, 14 figure

Quantum interference from remotely trapped ions

We observe quantum interference of photons emitted by two continuously laser-excited single ions, independently trapped in distinct vacuum vessels. High contrast two-photon interference is observed in two experiments with different ion species, calcium and barium. Our experimental findings are quantitatively reproduced by Bloch equation calculations. In particular, we show that the coherence of the individual resonance fluorescence light field is determined from the observed interference

Suppression of Magnetic Order by Pressure in BaFe2As2

We performed the dc resistivity and the ZF 75As-NMR measurement of BaFe2As2 under high pressure. The T-P phase diagram of BaFe2As2 determined from resistivity anomalies and the ZF 75As-NMR clearly revealed that the SDW anomaly is quite robust against P.Comment: 2 pages, 2 figure

Magnetic properties of iron pnictides from spin-spiral calculations

The wave-vector (q) and doping dependences of the magnetic energy, iron moment, and effective exchange interactions in LaFeAsO, BaFe2As2, and SrFe2As2\ are studied by self-consistent LSDA calculations for co-planar spin spirals. For the undoped compounds, the calculated total energy, E(q), reaches its minimum at q corresponding to stripe anti-ferromagnetic order. In LaFeAsO, this minimum becomes flat already at low levels of electron-doping and shifts to an incommensurate q at delta=0.2, where delta is the number of additional electrons (delta>0) or holes (delta<0) per Fe. In BaFe2As2 and SrFe2As2, stripe order remains stable for hole doping down to delta=-0.3. Under electron doping, on the other hand, the E(q) minimum shifts to incommensurate q already at delta=0.1.Comment: 4 pages, 2 figures, International Conference on Magnetism, Karlsruhe, July 26 - 31, 200

An X-ray Study of Two B+B Binaries: AH Cep and CW Cep

AH Cep and CW Cep are both early B-type binaries with short orbital periods of 1.8~d and 2.7~d, respectively. All four components are B0.5V types. The binaries are also double-lined spectroscopic and eclipsing. Consequently, solutions for orbital and stellar parameters make the pair of binaries ideal targets for a study of the colliding winds between two B~stars. {\em Chandra} ACIS-I observations were obtained to determine X-ray luminosities. AH~Cep was detected with an unabsorbed X-ray luminosity at a 90\% confidence interval of $(9-33)\times 10^{30}$ erg s$^{-1}$, or $(0.5-1.7)\times 10^{-7} L_{\rm Bol}$, relative to the combined Bolometric luminosities of the two components. While formally consistent with expectations for embedded wind shocks, or binary wind collision, the near-twin system of CW~Cep was a surprising non-detection. For CW~Cep, an upper limit was determined with $L_X/L_{\rm Bol} < 10^{-8}$, again for the combined components. One difference between these two systems is that AH~Cep is part of a multiple system. The X-rays from AH~Cep may not arise from standard wind shocks nor wind collision, but perhaps instead from magnetism in any one of the four components of the system. The possibility could be tested by searching for cyclic X-ray variability in AH~Cep on the short orbital period of the inner B~stars.Comment: Astrophysical Journal, accepte