Electrodynamic trapping of spinless neutral atoms with an atom chip

Three dimensional electrodynamic trapping of neutral atoms has been demonstrated. By applying time-varying inhomogeneous electric fields with micron-sized electrodes, nearly $10^2$ strontium atoms in the $^1S_0$ state have been trapped with a lifetime of 80 ms. In order to design the electrodes, we numerically analyzed the electric field and simulated atomic trajectories in the trap, which showed reasonable agreement with the experiment.Comment: 4pages, 4figures, to appear in Phys. Rev. Let

Thermally-induced magnetic phases in an Ising spin Kondo lattice model on a kagome lattice at 1/3-filling

Numerical investigation on the thermodynamic properties of an Ising spin Kondo lattice model on a kagome lattice is reported. By using Monte Carlo simulation, we investigated the magnetic phases at 1/3-filling. We identified two successive transitions from high-temperature paramagnetic state to a Kosterlitz-Thouless-like phase in an intermediate temperature range and to a partially disordered phase at a lower temperature. The partially disordered state is characterized by coexistence of antiferromagnetic hexagons and paramagnetic sites with period $\sqrt3 \times \sqrt3$. We compare the results with those for the triangular lattice case.Comment: 4 pages, 2 figure

Anti-Aquaporin-4 Antibody-Positive Neuromyelitis Optica Presenting with Syndrome of Inappropriate Antidiuretic Hormone Secretion as an Initial Manifestation

The distribution of neuromyelitis optica (NMO)-characteristic brain lesions corresponds to sites of high aquaporin-4 (AQP4) expression, and the brainstem and hypothalamus lesions that express high levels of AQP4 protein are relatively characteristic of NMO. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the important causes of hyponatremia and results from an abnormal production or sustained secretion of antidiuretic hormone (ADH). SIADH has been associated with many clinical states or syndromes, and the hypothalamic-neurohypophyseal system regulates the feedback control system for ADH secretion. We report the case of a 63-year-old man with NMO, whose initial manifestation was hyponatremia caused by SIADH. Retrospective analysis revealed that the serum anti-AQP4 antibody was positive, and an MRI scan showed a unilateral lesion in the hypothalamus. SIADH recovered completely with regression of the hypothalamic lesion. As such, NMO should even be considered in patients who develop SIADH and have no optic nerve or spinal cord lesions but have MRI-documented hypothalamic lesions

Bounded derived categories of very simple manifolds

An unrepresentable cohomological functor of finite type of the bounded derived category of coherent sheaves of a compact complex manifold of dimension greater than one with no proper closed subvariety is given explicitly in categorical terms. This is a partial generalization of an impressive result due to Bondal and Van den Bergh.Comment: 11 pages one important references is added, proof of lemma 2.1 (2) and many typos are correcte

Anomalous magnetic phase in an undistorted pyrochlore oxide Cd2Os2O7 induced by geometrical frustration

We report on the muon spin rotation/relaxation study of a pyrochlore oxide, Cd2Os2O7, which exhibits a metal-insulator (MI) transition at T_{MI}~225 K without structural phase transition. It reveals strong spin fluctuation (>10^8/s) below the MI transition, suggesting a predominant role of geometrical spin frustration amongst Os^{5+} ions. Meanwhile, upon further cooling, a static spin density wave discontinuously develops below T_{SDW}~150 K. These observations strongly suggest the occurrence of an anomalous magnetic transition and associated change in the local spin dynamics in undistorted pyrochlore antiferromagnet.Comment: 5 pages, 4 figure

Properties of the chiral spin liquid state in generalized spin ladders

We study zero temperature properties of a system of two coupled quantum spin chains subject to fields explicitly breaking time reversal symmetry and parity. Suitable choice of the strength of these fields gives a model soluble by Bethe Ansatz methods which allows to determine the complete magnetic phase diagram of the system and the asymptotics of correlation functions from the finite size spectrum. The chiral properties of the system for both the integrable and the nonintegrable case are studied using numerical techniques.Comment: 19 pages, 9eps figures, Late

Ordering of the Antiferromagnetic Heisenberg Model on a Pyrochlore Slab

Ordering of the geometrically frustrated two-dimensional Heisenberg antiferromagnet on a pyrochlore slab is studied by Monte Carlo simulations. The model is expected to serve as a reference system of SrCrGaO compound studied extensively. In sharp contrast to the kagom\'e Heisenberg antiferromagnet, the model exhibits locally non-coplanar spin structures at low temperatures, bearing nontrivial chiral degrees of freedom. We find that under certain conditions the model exhibits a novel Kosterlitz-Thouless-type transition at a finite temperature associated with these chiral degrees of freedom. Implications to experiments are discussed.Comment: 26 figure

Chiral Kosterlitz-Thouless transition in the frustrated Heisenberg antiferromagnet on a pyrochlore slab

Ordering of the geometrically frustrated two-dimensional Heisenberg antiferromagnet on a pyrochlore slab is studied by Monte Carlo simulations. In contrast to the kagom\'e Heisenberg antiferromagnet, the model exhibits locally non-coplanar spin structures at low temperatures, bearing nontrivial chiral degrees of freedom. Under certain conditions, the model exhibits a novel Kosterlitz-Thouless-type transition at a finite temperature associated with these chiral degrees of freedom