Local metrics admitting a principal Killing-Yano tensor with torsion

In this paper we initiate a classification of local metrics admitting the principal Killing--Yano tensor with a skew-symmetric torsion. It is demonstrated that in such spacetimes rank-2 Killing tensors occur naturally and mutually commute. We reduce the classification problem to that of solving a set of partial differential equations, and we present some solutions to these PDEs. In even dimensions, three types of local metrics are obtained: one of them naturally generalizes the torsionless case while the others occur only when the torsion is present. In odd dimensions, we obtain more varieties of local metrics. The explicit metrics constructed in this paper are not the most general possible admitting the required symmetry, nevertheless, it is demonstrated that they cover a wide variety of solutions of various supergravities, such as the Kerr-Sen black holes of (un-)gauged abelian heterotic supergravity, the Chong-Cvetic-L\"u-Pope black hole solution of five-dimensional minimal supergravity, or the K\"ahler with torsion manifolds. The relation between generalized Killing--Yano tensors and various torsion Killing spinors is also discussed.Comment: 36pages, no figure

On the Z_p-ranks of tamely ramified Iwasawa modules

For a prime number p, we denote by K the cyclotomic Z_p-extension of a number field k. For a finite set S of prime numbers, we consider the S-ramified Iwasawa module which is the Galois group of the maximal abelian pro-p-extension of K unramified outside S. This paper treats the case where S does not contain p and k is the rational number field or an imaginary quadratic field. In this case, we prove the explicit formulae for the free ranks of the S-ramified Iwasawa modules as abelian pro-p groups, by using Brumer's p-adic version of Baker's theorem on the linear independence of logarithms of algebraic numbers

Power-dependent internal loss in Josephson bifurcation amplifiers

We have studied nonlinear superconducting resonators: lambda/2 coplanar-waveguide (CPW) resonators with Josephson junctions (JJs) placed in the middle and lambda/4 CPW resonators terminated by JJs, which can be used for the qubit readout as "bifurcation amplifiers." The nonlinearity of the resonators arises from the Josephson junctions, and because of the nonlinearity, the resonators with appropriate parameters are expected to show a hysteretic response to the frequency sweep, or "bifurcation," when they are driven with a sufficiently large power. We designed and fabricated resonators whose resonant frequencies were around 10 GHz. We characterized the resonators at low temperatures, T<0.05 K, and confirmed that they indeed exhibited hysteresis. The sizes of the hysteresis, however, are sometimes considerably smaller than the predictions based on the loaded quality factor in the weak drive regime. When the discrepancy appears, it is mostly explained by taking into account the internal loss, which often increases in our resonators with increasing drive power in the relevant power range. As a possible origin of the power-dependent loss, the quasiparticle channel of conductance of the JJs is discussed.Comment: 8 pages, 9 figure

Bell inequalities stronger than the CHSH inequality for 3-level isotropic states

We show that some two-party Bell inequalities with two-valued observables are stronger than the CHSH inequality for 3 \otimes 3 isotropic states in the sense that they are violated by some isotropic states in the 3 \otimes 3 system that do not violate the CHSH inequality. These Bell inequalities are obtained by applying triangular elimination to the list of known facet inequalities of the cut polytope on nine points. This gives a partial solution to an open problem posed by Collins and Gisin. The results of numerical optimization suggest that they are candidates for being stronger than the I_3322 Bell inequality for 3 \otimes 3 isotropic states. On the other hand, we found no Bell inequalities stronger than the CHSH inequality for 2 \otimes 2 isotropic states. In addition, we illustrate an inclusion relation among some Bell inequalities derived by triangular elimination.Comment: 9 pages, 1 figure. v2: organization improved; less references to the cut polytope to make the main results clear; references added; typos corrected; typesetting style change

Simultaneously optimizing the interdependent thermoelectric parameters in Ce(Ni1−x_{1-x}Cux_x)2_2Al3_3

Substitution of Cu for Ni in the Kondo lattice system CeNi$_2$Al$_3$ results in a simultaneous optimization of the three interdependent thermoelectric parameters: thermoelectric power, electrical and thermal conductivities, where the electronic change in conduction band induced by the extra electron of Cu is shown to be crucial. The obtained thermoelectric figure of merit $zT$ amounts to 0.125 at around 100 K, comparable to the best values known for Kondo compounds. The realization of ideal thermoelectric optimization in Ce(Ni$_{1-x}$Cu$_x$)$_2$Al$_3$ indicates that proper electronic tuning of Kondo compounds is a promising approach to efficient thermoelectric materials for cryogenic application.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review

Demonstration of local expansion toward large-scale entangled webs

We demonstrate an optical gate that increases the size of polarization-based W states by accessing only one of the qubits. Using this gate, we have generated three-photon and four-photon W states with fidelities $0.836\pm 0.042$ and $0.784\pm 0.028$, respectively. We also confirmed existence of pairwise entanglement in every pair of the qubits including the one that was left untouched by the gate. The gate is applicable to any size of W states and hence is a universal tool for expanding entanglement.Comment: 5 pages, 4 figure

First Supramolecular Sensors for Phosphonate Anions

Fluorescent tripodal anion sensors with a 1,3,5-triethylbenzene core display a turn-on fluorescence response to phosphonate and phosphate anions and may be used as optical sensors. The properties of the receptors and sensors as well as their anion binding behavior were investigated both in solution and in solid state. The turn-on fluorescence response can be leveraged in sensing of phosphate anions and, most importantly, hydrolysis products of the nerve gas sarin, isopropyl methylphosphonate (IMP), and methylphosphonate (MP). The fluorescence signal amplification in the presence of anions allows for application of these molecules in a sensor microarray suitable for high-throughput screening.NSF CHE 0750303, EXP-LA 0731153BGSU (TIE Grant)Chemistr

M4 muscarinic receptor knockout mice display abnormal social behavior and decreased prepulse inhibition

<p>Abstract</p> <p>Background</p> <p>In the central nervous system (CNS), the muscarinic system plays key roles in learning and memory, as well as in the regulation of many sensory, motor, and autonomic processes, and is thought to be involved in the pathophysiology of several major diseases of the CNS, such as Alzheimer's disease, depression, and schizophrenia. Previous studies reveal that M₄muscarinic receptor knockout (M₄R KO) mice displayed an increase in basal locomotor activity, an increase in sensitivity to the prepulse inhibition (PPI)-disrupting effect of psychotomimetics, and normal basal PPI. However, other behaviorally significant roles of M₄R remain unclear.</p> <p>Results</p> <p>In this study, to further investigate precise functional roles of M₄R in the CNS, M₄R KO mice were subjected to a battery of behavioral tests. M₄R KO mice showed no significant impairments in nociception, neuromuscular strength, or motor coordination/learning. In open field, light/dark transition, and social interaction tests, consistent with previous studies, M₄R KO mice displayed enhanced locomotor activity compared to their wild-type littermates. In the open field test, M₄R KO mice exhibited novelty-induced locomotor hyperactivity. In the social interaction test, contacts between pairs of M₄R KO mice lasted shorter than those of wild-type mice. In the sensorimotor gating test, M₄R KO mice showed a decrease in PPI, whereas in the startle response test, in contrast to a previous study, M₄R KO mice demonstrated normal startle response. M₄R KO mice also displayed normal performance in the Morris water maze test.</p> <p>Conclusions</p> <p>These findings indicate that M₄R is involved in regulation of locomotor activity, social behavior, and sensorimotor gating in mice. Together with decreased PPI, abnormal social behavior, which was newly identified in the present study, may represent a behavioral abnormality related to psychiatric disorders including schizophrenia.</p