Nonlinear behavior of geometric phases induced by photon pairs

In this study, we observe the nonlinear behavior of the two-photon geometric phase for polarization states using time-correlated photons pairs. This phase manifests as a shift of two-photon interference fringes. Under certain arrangements, the geometric phase can vary nonlinearly and become very sensitive to a change in the polarization state. Moreover, it is known that the geometric phase for $N$ identically polarized photons is $N$ times larger than that for one photon. Thus, the geometric phase for two photons can become two times more sensitive to a state change. This high sensitivity to a change in the polarization can be exploited for precision measurement of small polarization variation. We evaluate the signal-to-noise ratio of the measurement scheme using the nonlinear behavior of the geometric phase under technical noise and highlight the practical advantages of this scheme.Comment: 10 pages, 10 figure

Dynamic fluctuations in the superconductivity of NbN films from microwave conductivity measurements

We have measured the frequency and temperature dependences of complex ac conductivity, \sigma(\omega)=\sigma_1(\omega)-i\sigma_2(\omega), of NbN films in zero magnetic field between 0.1 to 10 GHz using a microwave broadband technique. In the vicinity of superconducting critical temperature, Tc, both \sigma_1(\omega) and \sigma_2(\omega) showed a rapid increase in the low frequency limit owing to the fluctuation effect of superconductivity. For the films thinner than 300 nm, frequency and temperature dependences of fluctuation conductivity, \sigma(\omega,T), were successfully scaled onto one scaling function, which was consistent with the Aslamazov and Larkin model for two dimensional (2D) cases. For thicker films, \sigma(\omega,T) data could not be scaled, but indicated that the dimensional crossover from three dimensions (3D) to 2D occurred as the temperature approached Tc from above. This provides a good reference of ac fluctuation conductivity for more exotic superconductors of current interest.Comment: 8 pages, 7 Figures, 1 Table, Accepted for publication in PR

Scaling theory of transport in complex networks

Transport is an important function in many network systems and understanding its behavior on biological, social, and technological networks is crucial for a wide range of applications. However, it is a property that is not well-understood in these systems and this is probably due to the lack of a general theoretical framework. Here, based on the finding that renormalization can be applied to bio-networks, we develop a scaling theory of transport in self-similar networks. We demonstrate the networks invariance under length scale renormalization and we show that the problem of transport can be characterized in terms of a set of critical exponents. The scaling theory allows us to determine the influence of the modular structure on transport. We also generalize our theory by presenting and verifying scaling arguments for the dependence of transport on microscopic features, such as the degree of the nodes and the distance between them. Using transport concepts such as diffusion and resistance we exploit this invariance and we are able to explain, based on the topology of the network, recent experimental results on the broad flow distribution in metabolic networks.Comment: 8 pages, 6 figure

Geometrical parameter analysis of the high sensitivity fiber optic angular displacement sensor

In this work, we present an analysis of the influence of the geometrical parameters on the sensitivity and linear range of the fiber optic angular displacement sensor, through computational simulations and experiments. The geometrical parameters analyzed were the lens focal length, the gap between fibers, the fibers cladding radii, the emitting fiber critical angle (or, equivalently, the emitting fiber numerical aperture), and the standoff distance (distance between the lens and the reflective surface). Besides, we analyzed the sensor sensitivity regarding any spurious linear displacement. The simulation and experimental results showed that the parameters which play the most important roles are the emitting fiber core radius, the lens focal length, and the light coupling efficiency, while the remaining parameters have little influence on sensor characteristics. This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-53-36-8436. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Comment: 10 pages, 12 figure

Naturalized and simplified gauge mediation

Following recent developments in model building we construct a simple, natural and controllable model of gauge-mediated supersymmetry breaking.Comment: 8 pages, minor change

Mathematical structure of unit systems

We investigate the mathematical structure of unit systems and the relations between them. Looking over the entire set of unit systems, we can find a mathematical structure that is called preorder (or quasi-order). For some pair of unit systems, there exists a relation of preorder such that one unit system is transferable to the other unit system. The transfer (or conversion) is possible only when all of the quantities distinguishable in the latter system are always distinguishable in the former system. By utilizing this structure, we can systematically compare the representations in different unit systems. Especially, the equivalence class of unit systems (EUS) plays an important role because the representations of physical quantities and equations are of the same form in unit systems belonging to an EUS. The dimension of quantities is uniquely defined in each EUS. The EUS's form a partially ordered set. Using these mathematical structures, unit systems and EUS's are systematically classified and organized as a hierarchical tree.Comment: 27 pages, 3 figure

Measurement of the Superparticle Mass Spectrum in the Long-Lived Stau Scenario at the LHC

In supersymmetric scenarios with a long-lived stau, the LHC experiments provide us with a great environment for precise mass measurements of superparticles. We study a case in which the mass differences between the lightest stau and other sleptons are about 10 GeV or larger, so that the decay products of heavier sleptons are hard enough to be detected. We demonstrate that the masses of neutralinos, sleptons, and squarks can be measured with a good accuracy.Comment: 20 pages, 6 figure

Geometry of One-Dimensional Wave Propagation

We investigate the geometrical features of one-dimensional wave propagation, whose dynamics is described by the (2+1)-dimensional Lorentz group. We find many interesting geometrical ingredients such as spinorlike behavior of wave amplitudes, gauge transformations, Bloch-type equations, and Lorentz-group Berry phases. We also propose an optical experiment to verify these effects.Comment: RevTeX, 16 pages, 6 postscript figure