Nondiagonal Graphene Conductivity in the Presence of In-Plane Magnetic Fields

We study the electron/hole transport in puddle-disordered and rough graphene samples which are subject to in-plane magnetic fields. Previous treatments, mostly devoted to regimes where the electron/hole scattering wavelengths are larger than the surface height correlation length, are based on the use of transport equations with appropriate forms for the collision term. We point out in this work, as a counterpoint, that classical Lorentz force effects, which are expected to hold when the Fermi level is far enough away from the charge neutral point, can be heuristically assessed through disordered Boltzmann equations that contain magnetic-field dependent material derivatives, and keep the zero magnetic-field structure of the collision term. It turns out that the electric conductivity tensor gets a peculiar nondiagonal component, induced by the in-plane magnetic field that crosses the rough topography of the graphene sheet, even if the projected random transverse magnetic field vanishes in the mean. Numerical estimates of the transverse conductivities suggest that they are suitable of observation under conditions which are within the reach of up-to-date experimental methods.Comment: 14 pages, 2 figure

Inertial-Hall effect: the influence of rotation on the Hall conductivity

Inertial effects play an important role in classical mechanics but have been largely overlooked in quantum mechanics. Nevertheless, the analogy between inertial forces on mass particles and electromagnetic forces on charged particles is not new. In this paper, we consider a rotating non-interacting planar two-dimensional electron gas with a perpendicular uniform magnetic field and investigate the effects of the rotation in the Hall conductiv

Experimental implementation of a NMR entanglement witness

Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage. On this paper it is experimentally analyzed an entanglement witness recently proposed in the context of Nuclear Magnetic Resonance (NMR) experiments to test it in some Bell-diagonal states. We also propose some optimal entanglement witness for Bell-diagonal states. The efficiency of the two types of EW's are compared to a measure of entanglement with tomographic cost, the generalized robustness of entanglement. It is used a GRAPE algorithm to produce an entangled state which is out of the detection region of the EW for Bell-diagonal states. Upon relaxation, the results show that there is a region in which both EW fails, whereas the generalized robustness still shows entanglement, but with the entanglement witness proposed here with a better performance

Parmenidean Monism and The Routes of Being

Resum

Perspectivism and Conciliation in the Reading of Plato’s Dialogues

In recent decades, a growing number of scholars have questioned the developmental approach to Plato that dominated scholarship during the 20th century. In this context, old strategies of reading the dialogues have been renewed and new approaches proposed. Basically, three different reading strategies the dialogues have been advocated: the still dominant Developmentalism, Unitarianism, and the Literary (or Dramatic) reading. These different approaches are still largely taken as competitors and there seems to be no methodology available that systematically integrates these different readings. In this paper, I work upon the “Perspective reading” proposed by Kahn (2005), and Gonzales (2016) in order to present a methodology that integrates some aspects of these different approaches in a systematic and coherent way. -- Original in English.In recent decades, a growing number of scholars have questioned the developmental approach to Plato that dominated scholarship during the 20th century. In this context, old strategies of reading the dialogues have been renewed and new approaches proposed. Basically, three different reading strategies the dialogues have been advocated: the still dominant Developmentalism, Unitarianism, and the Literary (or Dramatic) reading. These different approaches are still largely taken as competitors and there seems to be no methodology available that systematically integrates these different readings. In this paper, I work upon the “Perspective reading” proposed by Kahn (2005), and Gonzales (2016) in order to present a methodology that integrates some aspects of these different approaches in a systematic and coherent way. Perspectivismo e Conciliação na Leitura dos Diálogos de Platão Nas últimas décadas, a abordagem desenvolvimentista da obra de Platão, que dominou a academia durante o século XX, tem sido progressivamente questionada. Nesse contexto, antigas estratégias de leitura dos diálogos foram renovadas e novas abordagens, propostas. Basicamente, três estratégias de leitura dos diálogos foram defendidas: a, ainda dominante, leitura desenvolvimentista, o unitarismo e a leitura literária (ou dramática). Essas diferentes abordagens ainda são amplamente consideradas como concorrentes e parece não haver metodologia disponível que integre essas diferentes leituras. Neste artigo, desenvolvo a “leitura de perspectivista” proposta por Kahn (2005) e Gonzales (2016), a fim de apresentar uma metodologia que integre aspectos importantes das três abordagens acima citadas de maneira sistemática e coerente. -- Original em inglês. &nbsp

Boundary-layer effects on electromagnetic and acoustic extraordinary transmission through narrow slits

We study the problem of resonant extraordinary transmission of electromagnetic and acoustic waves through subwavelength slits in an infinite plate, whose thickness is close to a half-multiple of the wavelength. We build on the matched-asymptotics analysis of Holley & Schnitzer (2019 Wave Motion91, 102381 (doi:10.1016/j.wavemoti.2019.102381)), who considered a single-slit system assuming an idealized formulation where dissipation is neglected and the electromagnetic and acoustic problems are analogous. We here extend that theory to include thin dissipative boundary layers associated with finite conductivity of the plate in the electromagnetic problem and viscous and thermal effects in the acoustic problem, considering both single-slit and slit-array configurations. By considering a distinguished boundary-layer scaling where dissipative and diffractive effects are comparable, we develop accurate analytical approximations that are generally valid near resonance; the electromagnetic–acoustic analogy is preserved up to a single parameter that is provided explicitly for both scenarios. The theory is shown to be in excellent agreement with GHz-microwave and kHz-acoustic experiments in the literature

Ciclo reprodutivo do apaiari, Astronotus ocellatus (Agassiz, 1831), como subsídio a sua utilização na piscicultura.

Resumo simples

Quantifying Quantum Correlations in Fermionic Systems using Witness Operators

We present a method to quantify quantum correlations in arbitrary systems of indistinguishable fermions using witness operators. The method associates the problem of finding the optimal entan- glement witness of a state with a class of problems known as semidefinite programs (SDPs), which can be solved efficiently with arbitrary accuracy. Based on these optimal witnesses, we introduce a measure of quantum correlations which has an interpretation analogous to the Generalized Robust- ness of entanglement. We also extend the notion of quantum discord to the case of indistinguishable fermions, and propose a geometric quantifier, which is compared to our entanglement measure. Our numerical results show a remarkable equivalence between the proposed Generalized Robustness and the Schliemann concurrence, which are equal for pure states. For mixed states, the Schliemann con- currence presents itself as an upper bound for the Generalized Robustness. The quantum discord is also found to be an upper bound for the entanglement.Comment: 7 pages, 6 figures, Accepted for publication in Quantum Information Processin

Faithful Squashed Entanglement

Squashed entanglement is a measure for the entanglement of bipartite quantum states. In this paper we present a lower bound for squashed entanglement in terms of a distance to the set of separable states. This implies that squashed entanglement is faithful, that is, strictly positive if and only if the state is entangled. We derive the bound on squashed entanglement from a bound on quantum conditional mutual information, which is used to define squashed entanglement and corresponds to the amount by which strong subadditivity of von Neumann entropy fails to be saturated. Our result therefore sheds light on the structure of states that almost satisfy strong subadditivity with equality. The proof is based on two recent results from quantum information theory: the operational interpretation of the quantum mutual information as the optimal rate for state redistribution and the interpretation of the regularised relative entropy of entanglement as an error exponent in hypothesis testing. The distance to the set of separable states is measured by the one-way LOCC norm, an operationally-motivated norm giving the optimal probability of distinguishing two bipartite quantum states, each shared by two parties, using any protocol formed by local quantum operations and one-directional classical communication between the parties. A similar result for the Frobenius or Euclidean norm follows immediately. The result has two applications in complexity theory. The first is a quasipolynomial-time algorithm solving the weak membership problem for the set of separable states in one-way LOCC or Euclidean norm. The second concerns quantum Merlin-Arthur games. Here we show that multiple provers are not more powerful than a single prover when the verifier is restricted to one-way LOCC operations thereby providing a new characterisation of the complexity class QMA.Comment: 24 pages, 1 figure, 1 table. Due to an error in the published version, claims have been weakened from the LOCC norm to the one-way LOCC nor