Scaling and width distributions of parity-conserving interfaces

We present an alternative finite-size approach to a set of parity-conserving interfaces involving attachment, dissociation, and detachment of extended objects in 1+1 dimensions. With the aid of a nonlocal construct introduced by Barma and Dhar in related systems [Phys. Rev. Lett. 73, 2135 (1994)], we circumvent the subdiffusive dynamics and examine close-to-equilibrium aspects of these interfaces by assembling states of much smaller, numerically accessible scales. As a result, roughening exponents, height correlations, and width distributions exhibiting universal scaling functions are evaluated for interfaces virtually grown out of dimers and trimers on large-scale substrates. Dynamic exponents are also studied by finite-size scaling of the spectrum gaps of evolution operators.Fil: Arlego, Marcelo José Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Grynberg, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentin

Series Expansion Analysis of a Frustrated Four-Spin-Tube

We study the magnetism of a frustrated four-leg spin-1/2 ladder with transverse periodic boundary conditions: the frustrated four-spin tube (FFST). Using a combination of series expansion (SE), based on the continuous unitary transformation method and density-matrix renormalization group (DMRG) we analyze the ground-state, the one-, and the two-particle excitations in the regime of strong rung-coupling. We find several marked differences of the FFST with respect to standard two-leg ladders. First we show that frustration destabilizes the spin-gap phase of the FFST which is adiabatically connected to the limit of decoupled rung singlets, leading to a first order quantum phase transition at finite inter-rung coupling. Second, we show that apart from the well-know triplon branch of spin-ladders, the FFST sustains additional elementary excitations, including a singlon, and additional triplons. Finally we find, that in the two-particle sector the FFST exhibits collective (anti)bound states similar to two-leg ladders, however with a different ordering of the spin-quantum numbers. We show that frustration has significant impact on the FFST leading to a flattening of the ground-state energy landscape, a mass-enhancement of the excitations, and to a relative enhancement of the (anti)binding strength. Where possible we use DMRG to benchmark the findings from our SE calculations, showing excellent agreement.Comment: 10 pages, 10 figure

Scaling and width distributions of parity-conserving interfaces

We present an alternative finite-size approach to a set of parity-conserving interfaces involving attachment, dissociation, and detachment of extended objects in 1+1 dimensions. With the aid of a nonlocal construct introduced by Barma and Dhar in related systems [Phys. Rev. Lett. 73, 2135 (1994)], we circumvent the subdiffusive dynamics and examine close-to-equilibrium aspects of these interfaces by assembling states of much smaller, numerically accessible scales. As a result, roughening exponents, height correlations, and width distributions exhibiting universal scaling functions are evaluated for interfaces virtually grown out of dimers and trimers on large-scale substrates. Dynamic exponents are also studied by finite-size scaling of the spectrum gaps of evolution operators.Facultad de Ciencias ExactasDepartamento de Físic

Quantum phase diagram of a frustrated antiferromagnet on the bilayer honeycomb lattice

We study the spin-1/2 Heisenberg antiferromagnet on a bilayer honeycomb lattice including interlayer frustration. Using a set of complementary approaches, namely Schwinger bosons, dimer series expansion, bond operators, and exact diagonalization, we map out the quantum phase diagram. Analyzing ground state energies and elementary excitation spectra, we find four distinct phases, corresponding to three collinear magnetic long range ordered states, and one quantum disordered interlayer dimer phase. We detail, that the latter phase is adiabatically connected to an "exact" singlet product ground state of the the bilayer which exists along a line of maximum interlayer frustration. The order within the remaining three phases will be clarified.Comment: 12 pages, 12 figure

Series expansion analysis of a frustrated four-spin tube

We study the magnetism of a frustrated four-leg spin-1/2 ladder with transverse periodic boundary conditions: the frustrated four-spin tube (FFST). Using a combination of series expansion (SE), based on the continuous unitary transformation method and density-matrix renormalization group (DMRG) we analyze the ground-state, the one-, and the two-particle excitations in the regime of strong rung coupling. We find several marked differences of the FFST with respect to standard two-leg ladders. First, we show that frustration destabilizes the spin-gap phase of the FFST, which is adiabatically connected to the limit of decoupled rung singlets, leading to a first-order quantum phase transition at finite interrung coupling. Second, we show that apart from the well-known triplon branch of spin ladders, the FFST sustains additional elementary excitations, including a singlon and additional triplons. Finally, we find that in the two-particle sector, the FFST exhibits collective (anti)bound states similar to two-leg ladders, however, with a different ordering of the spin-quantum numbers. We show that frustration has significant impact on the FFST leading to a flattening of the ground-state energy landscape, a mass-enhancement of the excitations, and to a relative enhancement of the (anti)binding strength. Where possible, we use DMRG to benchmark the findings from our SE calculations, showing excellent agreement.Facultad de Ciencias Exacta

Quasiperiodic spin chains in a magnetic field

We study the interplay between a (quasi) periodic coupling array and an external magnetic field in a spin-1/2 XXZ chain. A new class of magnetization plateau is obtained by means of Abelian bosonization methods which gives rise to a sufficient quantization condition. The investigation of magnetic phase diagrams via exact diagonalization of finite clusters finds a complete agreement with the continuum treatment in a variety of situations.Instituto de Física La Plat

El rol de la historia de las ciencias en la enseñanza del cálculo vectorial en carreras de ingeniería

En este trabajo presentamos una posible estrategia didáctica para la enseñanza del cálculo vectorial en carreras de ingeniería. La misma aborda una perspectiva histórica, contextualizando los conceptos matemáticos con el conjunto de fenómenos físicos que motivaron su origen. Para ello, exponemos una reseña de los orígenes del cálculo vectorial durante los siglos XVIII y XIX. Se consideran reflexiones de investigadores enfatizando la importancia de incorporar aspectos epistemológicos e historiográficos, en la enseñanza de las ciencias

El rol de la historia de las ciencias en la enseñanza del cálculo vectorial en carreras de ingeniería

En este trabajo presentamos una posible estrategia didáctica para la enseñanza del Cálculo Vectorial en carreras de Ingeniería. La misma aborda una perspectiva histórica, contextualizando los conceptos matemáticos con el conjunto de fenómenos físicos que motivaron su origen. Para ello, exponemos una reseña de los orígenes del Cálculo Vectorial durante los siglos XVIII y XIX. Se consideran reflexiones de investigadores enfatizando la importancia de incorporar aspectos epistemológicos e historiográficos, en la enseñanza de las ciencias.In this work we present a possible didactic strategy for teaching vector calculus in engineering careers. It addresses a historical perspective, contextualizing mathematical concepts with physical phenomena that led to its origin. To this end, we present an overview of the origin of vector calculus during the eighteenth and nineteenth centuries. We consider reflections of researchers emphasizing the importance of incorporating epistemological and historiographical aspects in science education.Neste trabalho apresentamos uma possível estratégia didática para o ensino de cálculo vetorial em carreiras de engenharia. Ele aborda uma perspectiva histórica, contextualizando os conceitos matemáticos com fenômenos físicos que levaram à sua origem. Para este fim, apresentamos uma visão geral da origem do cálculo vetorial, durante os séculos XVIII e XIX. Finalmente, consideramos as reflexões de pesquisadores, enfatizando a importância de incorporar aspectos epistemológicos e historiográficos em educação científica.Fil: Costa, Viviana Angélica. Universidad Nacional de La Plata. Facultad de Ingenieria; ArgentinaFil: Arlego, Marcelo José Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata; Argentin

Los fundamentos de la mecánica cuántica en la escuela secundaria utilizando el concepto de integral de camino

Analizamos las posibilidades de introducir las ideas básicas de la mecánica cuántica en la escuela secundaria, adaptando los conceptos de la formulación de integrales de camino (path integrals) para los estudiantes. Este trabajo focaliza en el fundamento teórico de la propuesta y en las adaptaciones necesarias para una posible implementación de esta en un curso del último año.We analyze the possibilities of introducing the basic ideas of quantum mechanics into secondary school, by adapting the path integral formulation’s concepts for the students. This work focuses on this proposal’s theoretical basis and what aspects of the formalism should be adapted in order to be implemented in the last year’s course.Instituto de Física La Plat

Relativity of simultaneity in secondary school: an analysis based on the theory of the conceptual fields

In this paper, we present results about the conceptualization of the relativity of simultaneity and the operational invariants used by high school students. The Theory of Conceptual Fields is adopted to design, analyse and evaluate a didactic sequence to teach the basic aspects of the Theory of Special Relativity in secondary school. Only the situations related to the relativity of simultaneity are analysed here. An inductive categorization is constructed from 256 protocols generated in the implementations carried out in four 11th grade courses (15-16 years) (N = 128) in a public school of Colombia. The categorization identifies the resolutions of the students and the operative invariants that they use in each situation. The results indicate that the proposed situations would produce the emergence and awareness of the operational invariants linked to the relativity of Galileo, which would open the way to the conceptualization of the relativity of simultaneity in secondary school.Fil: Otero, Maria Rita. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Núcleo de Investigación en Educacion Ciencia y Tecnologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Arlego, Marcelo José Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin