On Some Positivity Properties of the Interquark Potential in QCD

We prove that the Fourier transform of the exponential e^{-\b V(R)} of the {\bf static} interquark potential in QCD is positive. It has been shown by Eliott Lieb some time ago that this property allows in the same limit of static spin independent potential proving certain mass relation between baryons with different quark flavors.Comment: 6 pages, latex with one postscript figur

Harvesting Entities from the Web Using Unique Identifiers -- IBEX

In this paper we study the prevalence of unique entity identifiers on the Web. These are, e.g., ISBNs (for books), GTINs (for commercial products), DOIs (for documents), email addresses, and others. We show how these identifiers can be harvested systematically from Web pages, and how they can be associated with human-readable names for the entities at large scale. Starting with a simple extraction of identifiers and names from Web pages, we show how we can use the properties of unique identifiers to filter out noise and clean up the extraction result on the entire corpus. The end result is a database of millions of uniquely identified entities of different types, with an accuracy of 73--96% and a very high coverage compared to existing knowledge bases. We use this database to compute novel statistics on the presence of products, people, and other entities on the Web.Comment: 30 pages, 5 figures, 9 tables. Complete technical report for A. Talaika, J. A. Biega, A. Amarilli, and F. M. Suchanek. IBEX: Harvesting Entities from the Web Using Unique Identifiers. WebDB workshop, 201

The state space for two qutrits has a phase space structure in its core

We investigate the state space of bipartite qutrits. For states which are locally maximally mixed we obtain an analog of the ``magic'' tetrahedron for bipartite qubits--a magic simplex W. This is obtained via the Weyl group which is a kind of ``quantization'' of classical phase space. We analyze how this simplex W is embedded in the whole state space of two qutrits and discuss symmetries and equivalences inside the simplex W. Because we are explicitly able to construct optimal entanglement witnesses we obtain the border between separable and entangled states. With our method we find also the total area of bound entangled states of the parameter subspace under intervestigation. Our considerations can also be applied to higher dimensions.Comment: 3 figure

Triaxial frequency sweep characterization for dense graded hot mix asphalt concrete mix design

Asphalt concrete mix design methods, such as the Marshall method, have historically been based on physical and phenomenological material testing empirically correlated to observed field performance. Changing pavement field state conditions such as increased trucking, poorer quality aggregate resources, and the aged state of road infrastructure in Saskatchewan have resulted in recent pavement performance to be outside traditional empirical performance prediction inference. It has been recognized worldwide that a mechanistic based asphalt concrete mix design methodology that directly quantifies structural behaviour of pavement under diverse field state conditions could significantly assist pavement design engineers. However, SHRP Level II and III mechanistic asphalt concrete characterization has been shown not to be pragmatic for characterizing asphalt concrete mixes. The objective of this research was to investigate the use of mechanistic material properties obtained from triaxial frequency sweep characterization in the rapid triaxial tester (RaTT) in conjunction with SHRP gyratory compaction properties for designing asphalt concrete for different asphalt cement contents, traffic loads, traffic speeds, and temperatures. RaTT testing was more responsive to variation in asphalt cement content outside of acceptable ranges of volumetric properties relative to Marshall stability and flow. This demonstrated the importance of specifying acceptable volumetric properties of asphalt concrete mixes. Correlation of material properties with volumetric measurements validated triaxial frequency sweep characterization in the RaTT. Dynamic modulus, Poisson’s ratio, and phase angle results were in accordance with expected material behaviour, indicating that the RaTT provides reasonable asphalt concrete material properties. Also, the RaTT identified asphalt concrete to be a nonlinear viscoelastic material, as observed in the field. The RaTT was able to characterize SHRP gyratory compacted samples for the typical range of traction states, load frequencies, and temperatures that simulated a range of Saskatchewan field state conditions. Triaxial frequency sweep testing in the RaTT could significantly augment conventional volumetric mix analysis as well as the SHRP SuperpaveTM Level I asphalt concrete mix design system. RaTT testing was found to be cost effective, time efficient, and provided mechanistic material constitutive relations that can be employed for inelastic mechanistic mix design, road structural modelling, and asset management

Optical imaging of resonant electrical carrier injection into individual quantum dots

We image the micro-electroluminescence (EL) spectra of self-assembled InAs quantum dots (QDs) embedded in the intrinsic region of a GaAs p-i-n diode and demonstrate optical detection of resonant carrier injection into a single QD. Resonant tunneling of electrons and holes into the QDs at bias voltages below the flat-band condition leads to sharp EL lines characteristic of individual QDs, accompanied by a spatial fragmentation of the surface EL emission into small and discrete light- emitting areas, each with its own spectral fingerprint and Stark shift. We explain this behavior in terms of Coulomb interaction effects and the selective excitation of a small number of QDs within the ensemble due to preferential resonant tunneling paths for carriers.Comment: 4 page

A second eigenvalue bound for the Dirichlet Schroedinger operator

Let $\lambda_i(\Omega,V)$ be the $i$th eigenvalue of the Schr\"odinger operator with Dirichlet boundary conditions on a bounded domain $\Omega \subset \R^n$ and with the positive potential $V$. Following the spirit of the Payne-P\'olya-Weinberger conjecture and under some convexity assumptions on the spherically rearranged potential $V_\star$, we prove that $\lambda_2(\Omega,V) \le \lambda_2(S_1,V_\star)$. Here $S_1$ denotes the ball, centered at the origin, that satisfies the condition $\lambda_1(\Omega,V) = \lambda_1(S_1,V_\star)$. Further we prove under the same convexity assumptions on a spherically symmetric potential $V$, that $\lambda_2(B_R, V) / \lambda_1(B_R, V)$ decreases when the radius $R$ of the ball $B_R$ increases. We conclude with several results about the first two eigenvalues of the Laplace operator with respect to a measure of Gaussian or inverted Gaussian density

Modeling Quantum Optical Components, Pulses and Fiber Channels Using OMNeT++

Quantum Key Distribution (QKD) is an innovative technology which exploits the laws of quantum mechanics to generate and distribute unconditionally secure cryptographic keys. While QKD offers the promise of unconditionally secure key distribution, real world systems are built from non-ideal components which necessitates the need to model and understand the impact these non-idealities have on system performance and security. OMNeT++ has been used as a basis to develop a simulation framework to support this endeavor. This framework, referred to as "qkdX" extends OMNeT++'s module and message abstractions to efficiently model optical components, optical pulses, operating protocols and processes. This paper presents the design of this framework including how OMNeT++'s abstractions have been utilized to model quantum optical components, optical pulses, fiber and free space channels. Furthermore, from our toolbox of created components, we present various notional and real QKD systems, which have been studied and analyzed.Comment: Published in: A. F\"orster, C. Minkenberg, G. R. Herrera, M. Kirsche (Eds.), Proc. of the 2nd OMNeT++ Community Summit, IBM Research - Zurich, Switzerland, September 3-4, 201