6,616 research outputs found
Selective cloning of Gaussian states by linear optics
We investigate the performances of a selective cloning machine based on
linear optical elements and Gaussian measurements, which allows to clone at
will one of the two incoming input states. This machine is a complete
generalization of a 1 to 2 cloning scheme demonstrated by U. L. Andersen et al.
[Phys. Rev. Lett. vol. 94, 240503 (2005)]. The input-output fidelity is studied
for generic Gaussian input state and the effect of non-unit quantum efficiency
is also taken into account. We show that if the states to be cloned are
squeezed states with known squeezing parameter, then the fidelity can be
enhanced using a third suitable squeezed state during the final stage of the
cloning process. A binary communication protocol based on the selective cloning
machne is also discussed.Comment: 6 pages, 6 figure
Automatic assessment of creativity in heuristic problem-solving based on query diversity
Indexación: Web of Science; Scopus.Research, development and innovation are the pillars on which companies rely to offer new products and services capable of attracting consumer demand. This is why creative problem-solving emerges as one of the most relevant skills of the 21st century. Fortunately, there are many creativity training programs that have proven effective. However, many of these programs and methods base on a previous measurement of creativity and require experienced reviewers, they consume time for being manual, and they are far from everyday activities. In this study, we propose a model to estimate the creative quality of users' solutions dealing with heuristic problems, based on the automatic analysis of query patterns issued during the information search to solve the problem. This model has been able to predict the creative quality of solutions produced by 226 users, reaching a sensitivity of 78.43%. Likewise, the level of agreement among reviewers in relation to the creative characteristics is evaluated through two rubrics, and thereby, observing the difficulties of the manual evaluation: subjectivity and effort. The proposed model could be used to foster prompt detection of non-creative solutions and it could be implemented in diverse industrial processes that can range from the recruitment of talent to the evaluation of performance in R&D&I processes.https://www.revistadyna.com/search/automatic-assessment-of-creativity-in-heuristic-problem-solving-based-on-query-diversit
Characterization of qubit chains by Feynman probes
We address the characterization of qubit chains and assess the performances
of local measurements compared to those provided by Feynman probes, i.e.
nonlocal measurements realized by coupling a single qubit regis- ter to the
chain. We show that local measurements are suitable to estimate small values of
the coupling and that a Bayesian strategy may be successfully exploited to
achieve optimal precision. For larger values of the coupling Bayesian local
strategies do not lead to a consistent estimate. In this regime, Feynman probes
may be exploited to build a consistent Bayesian estimator that saturates the
Cram\'er-Rao bound, thus providing an effective characterization of the chain.
Finally, we show that ultimate bounds to precision, i.e. saturation of the
quantum Cram\'er-Rao bound, may be achieved by a two-step scheme employing
Feynman probes followed by local measurements.Comment: 8 pages, 5 figure
Modelling and Controlling the Kinetic and Dynamic of a Bicycle
En este trabajo, se presenta el modelado y control posterior de una mini-bicicleta autónoma, que se utilizará para la enseñanza de sistemas de control. El modelo mecánico se construye inicialmente a partir de un diseño CAD y posteriormente se integra en Simulink, conjuntamente con los módulos de control. Se lleva a cabo el modelado del sistema completo, incluyendo las partes mecánicas, sensores, actuadores y la fricción de las ruedas con el suelo, consiguiéndose el mismo comportamiento que con la bicicleta fÃsica. A partir de las ecuaciones matemáticas que definen el comportamiento del sistema se diseña un controlador PID y un controlador LQG en el espacio de estados. Para verificar el modelo, los controladores diseñados se prueban también con los mismos parámetros en la mini-bicicleta fÃsica, obteniéndose un resultado idéntico.In this work, the modeling and subsequent control of an autonomous mini-bicycle is presented, which will be used for the teaching of control systems. The mechanical model is initially built from a CAD design and then integrated into Simulink, together with the control modules. The modeling of the complete system is carried out, including the mechanical parts, sensors, actuators and the friction of the wheels with the ground, achieving the same behavior as with the physical bicycle. From the mathematical equations that define the behavior of the system, a PID controller and an LQG controller are designed in the state space. To verify the model, the designed controllers are also tested with the same parameters in the physical mini-bicycle, obtaining an identical result.Universidad de Granada: Departamento de Arquitectura y TecnologÃa de Computadore
Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP67851 c
Precision radial velocities are required to discover and characterize planets
orbiting nearby stars. Optical and near infrared spectra that exhibit many
hundreds of absorption lines can allow the m/s precision levels required for
such work. However, this means that studies have generally focused on
solar-type dwarf stars. After the main-sequence, intermediate-mass stars
(former A-F stars) expand and rotate slower than their progenitors, thus
thousands of narrow absorption lines appear in the optical region, permitting
the search for planetary Doppler signals in the data for these types of stars.
We present the discovery of two giant planets around the intermediate-mass
evolved star HIP65891 and HIP107773. The best Keplerian fit to the HIP65891 and
HIP107773 radial velocities leads to the following orbital parameters: P=1084.5
d; msin = 6.0 M; =0.13 and P=144.3 d; msin = 2.0
M; =0.09, respectively. In addition, we confirm the planetary nature
of the outer object orbiting the giant star HIP67851. The orbital parameters of
HIP67851c are: P=2131.8 d, msin = 6.0 M and =0.17. With
masses of 2.5 M and 2.4 M HIP65891 and HIP107773 are two of the
most massive stars known to host planets. Additionally, HIP67851 is one of five
giant stars that are known to host a planetary system having a close-in planet
( 0.7 AU). Based on the evolutionary states of those five stars, we
conclude that close-in planets do exist in multiple systems around subgiants
and slightly evolved giants stars, but probably they are subsequently destroyed
by the stellar envelope during the ascent of the red giant branch phase. As a
consequence, planetary systems with close-in objects are not found around
horizontal branch stars.Comment: Accepted for publication in A&
Heat conduction in chains of non-locally coupled harmonic oscillators: mean-field limit
We consider one-dimensional systems of all-to-all harmonically coupled
particles with arbitrary masses, subject to two Langevin thermal baths. The
couplings correspond to the mean-field limit of long-range interactions.
Additionally, the particles can be subject to a harmonic on-site potential to
break momentum conservation. Using the non-equilibrium Green operator
formalism, we calculate the transmittance, the heat flow and local
temperatures, for arbitrary configurations of masses. For identical masses, we
show analytically that, the heat flux decays with the system size , as
, regardless of the conservation or not of the momentum, and of the
introduction or not of a Kac factor. These results describe in good agreement
the thermal behavior of systems with small heterogeneity in the masses.Comment: 6 pages, 5 figure
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