484 research outputs found
Highly-efficient noise-assisted energy transport in classical oscillator systems
Photosynthesis is a biological process that involves the highly-efficient
transport of energy captured from the sun to a reaction center, where
conversion into useful biochemical energy takes place. Even though one can
always use a quantum perspective to describe any physical process, since
everything follows the laws of Quantum Mechanics, is the use of quantum theory
imperative to explain this high efficiency? Making use of the quantum-classical
correspondence of electronic energy transfer recently introduced by Eisfeld and
Briggs [Phys. Rev. E 85, 046118 (2012)], we show here that the highly-efficient
noise-assisted energy transport described by Rebentrost et al. [New J. Phys.
11, 033003 (2009)], and Plenio and Huelga [New J. Phys. 10, 113019 (2008)], as
the result of the interplay between the quantum coherent evolution of the
photosynthetic system and noise introduced by its surrounding environment, it
can be found as well in purely classical systems. The wider scope of
applicability of the enhancement of energy transfer assisted by noise might
open new ways for developing new technologies aimed at enhancing the efficiency
of a myriad of energy transfer systems, from information channels in
micro-electronic circuits to long-distance high-voltage electrical lines.Comment: 4 pages, 3 figure
Un entorno geométrico para la resignificación de las razones trigonométricas en estudiantes de ingeniería
La necesidad de organizar un nuevo escenario escolar para abordar lo trigonométrico, que no separara tajantemente el contexto geométrico de las razones del contexto analítico de las funciones, provocó la búsqueda por lograr la significación progresiva de las razones trigonométricas en estudiantes de Ingeniería del Instituto Tecnológico de Sonora (ITSON). En ese sentido, se caracterizaron las propuestas de Moore (2009, 2010 y 2014) y de Vohns (2006), ya que permiten su significación progresiva en el contexto del círculo, principalmente porque devuelven a lo trigonométrico su naturaleza geométrica (Montiel, 2013). La perspectiva constructivista de Moore y el diseño de Vohns se articulan con la epistemología basada en la actividad que proponen Montiel (2011), Montiel (2013), Montiel y Jácome (en prensa), lo cual permitió el análisis de las dificultades y las construcciones de lo trigonométrico desde un enfoque teórico de corte social
Coherent delocalization: Views of entanglement in different scenarios
The concept of entanglement was originally introduced to explain correlations
existing between two spatially separated systems, that cannot be described
using classical ideas. Interestingly, in recent years, it has been shown that
similar correlations can be observed when considering different degrees of
freedom of a single system, even a classical one. Surprisingly, it has also
been suggested that entanglement might be playing a relevant role in certain
biological processes, such as the functioning of pigment-proteins that
constitute light-harvesting complexes of photosynthetic bacteria. The aim of
this work is to show that the presence of entanglement in all of these
different scenarios should not be unexpected, once it is realized that the very
same mathematical structure can describe all of them. We show this by
considering three different, realistic cases in which the only condition for
entanglement to exist is that a single excitation is coherently delocalized
between the different subsystems that compose the system of interest
Star product approach for Loop Quantum Cosmology
Guided by recent developments towards the implementation of the deformation
quantization program within the Loop Quantum Cosmology (LQC) formalism, in this
paper we address the introduction of both the integral and differential
representation of the star product for LQC. To this end, we consider the Weyl
quantization map for cylindrical functions defined on the Bohr compactification
of the reals. The integral representation contains all of the common properties
that characterize a star product which, in the case under study here, stands
for a deformation of the usual pointwise product of cylindrical functions. Our
construction also admits a direct comparison with the integral representation
of the Moyal product which may be reproduced from our formulation by
judiciously substituting the appropriate characters that identify such
representation. Further, we introduce a suitable star commutator that correctly
reproduces both the quantum representation of the holonomy-flux algebra for LQC
and, in the proper limit, the holonomy-flux classical Poisson algebra emerging
in the cosmological setup. Finally, we propose a natural way to obtain the
quantum dynamical evolution in LQC in terms of this star commutator for
cylindrical functions as well as a differential representation of the star
product using discrete finite differences. We expect that our findings may
contribute to a better understanding of certain issues arising within the LQC
program, in particular, those related to the semiclassical limit and the
dynamical evolution of quantum states.Comment: 21 pages, no figure
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