Carrier-envelope phase dependence in single-cycle laser pulse propagation with the inclusion of counter-rotating terms

We focus on the propagation properties of a single-cycle laser pulse through a two-level medium by numerically solving the full-wave Maxwell-Bloch equations. The counter-rotating terms in the spontaneous emission damping are included such that the equations of motion are slightly different from the conventional Bloch equations. The counter-rotating terms can considerably suppress the broadening of the pulse envelope and the decrease of the group velocity rooted from dispersion. Furthermore, for incident single-cycle pulses with envelope area 4$\pi$, the time-delay of the generated soliton pulse from the main pulse depends crucially on the carrier-envelope phase of the incident pulse. This can be utilized to determine the carrier-envelope phase of the single-cycle laser pulse.Comment: 6 pages, 5 figure

Student experiences of virtual reality - a case study in learning special relativity

We present a study of student learning through the use of virtual reality. A software package is used to introduce concepts of special relativity to students in a game-like environment where users experience the effects of travelling at near light speeds. From this new perspective, space and time are significantly different to that experienced in everyday life. The study explores how students have worked with this environment and how these students have used this experience in their study of special relativity. A mixed method approach has been taken to evaluate the outcomes of separate implementations of the package at two universities. Students found the simulation to be a positive learning experience and described the subject area as being less abstract after its use. Also, students were more capable of correctly answering concept questions relating to special relativity, and a small but measurable improvement was observed in the final exam

Optimal Depth, Very Small Size Circuits for Symmetrical Functions in AC0

AbstractIt is well known which symmetric Boolean functions can be computed by constant depth, polynomial size, unbounded fan-in circuits, i.e., which are contained in the complexity class AC0. This result is sharpened. Symmetric Boolean functions in AC0 can be computed by unbounded fan-in circuits with the following properties. If the optimal depth of AC0-circuits is d, the depth is at most d + 2, the number of wires is almost linear, namely n logO(1)n, and the number of gates is subpolynomial (but superpolylogarithmic), namely 2O(logδn) for some δ < 1

Magnetic metamaterials at telecommunication and visible frequencies

Arrays of gold split-rings with 50-nm minimum feature size and with an LC resonance at 200-THz frequency (1500-nm wavelength) are fabricated. For normal incidence conditions, they exhibit a pronounced fundamental magnetic mode, arising from a coupling via the electric component of the incident light. For oblique incidence, a coupling via the magnetic component is demonstrated as well. Moreover, we identify a novel higher-order magnetic resonance at around 370 THz (800-nm wavelength) that evolves out of the Mie resonance for oblique incidence. Comparison with theory delivers good agreement and also shows that the structures allow for a negative magnetic permeability.Comment: 4 pages, 3 figure

Novedades sobre el poblamiento antiguo en la parte navarra de la Val d’Onsella

El presente trabajo recoge un análisis basado en arqueología espacial llevado a cabo en el Valle del río Onsella, en el límite entre Navarra y Aragón. Se establecen las pautas de ocupación del territorio desde la Segunda Edad del Hierro hasta la tardoantigüedad, prestando especial atención al periodo romano, que marca un momento de profunda transformación y fuerte dinamismo. El espacio se configura en torno al enclave de carácter urbano de Fi- llera/Campo Real (Sos del Rey Católico, Zaragoza) y en menor medida en torno al posible vicus de Cementerio de Gordún (Gordún, Zaragoza).The present comunication summarizes an spatial archaeology analysis executed on the Onsella’s valley, placed betwen Navarra and Aragón.Guidelines are established on the occupation of the territory from the Second Iron Age to the Late Antiquity, with particular attention to the Roman period, being a remarkable time of deep transformation and strong dynamism. The space set around an urban site of Fillera/Campo Real and less on the possible vicus ofCementerio de Gordún

Verifying proofs in constant depth

In this paper we initiate the study of proof systems where verification of proofs proceeds by NC circuits. We investigate the question which languages admit proof systems in this very restricted model. Formulated alternatively, we ask which languages can be enumerated by NC functions. Our results show that the answer to this problem is not determined by the complexity of the language. On the one hand, we construct NC proof systems for a variety of languages ranging from regular to NP-complete. On the other hand, we show by combinatorial methods that even easy regular languages such as Exact-OR do not admit NC proof systems. We also present a general construction of proof systems for regular languages with strongly connected NFA's

Origin of temperature dependent conductivity of α\alpha-polyvinylidene fluoride

The conductivity of $\alpha$-polyvinylidene fluoride ($\alpha$-PVDF) is obtained from dielectric measurements performed in the frequency domain at several temperatures. At temperatures above the glass-transition, the conductivity can be interpreted as an ionic conductivity, which confirms earlier results reported in the literature. Our investigation shows that the observed ionic conductivity is closely related to the amorphous phase of the polymer