Quantum Ratchets for Quantum Communication with Optical Superlattices

We propose to use a quantum ratchet to transport quantum information in a chain of atoms trapped in an optical superlattice. The quantum ratchet is created by a continuous modulation of the optical superlattice which is periodic in time and in space. Though there is zero average force acting on the atoms, we show that indeed the ratchet effect permits atoms on even and odd sites to move along opposite directions. By loading the optical lattice with two-level bosonic atoms, this scheme permits to perfectly transport a qubit or entangled state imprinted in one or more atoms to any desired position in the lattice. From the quantum computation point of view, the transport is achieved by a smooth concatenation of perfect swap gates. We analyze setups with noninteracting and interacting particles and in the latter case we use the tools of optimal control to design optimal modulations. We also discuss the feasibility of this method in current experiments.Comment: Published version, 9 pages, 5 figure

RESEARCH IN ECONOMICS IN SPAIN: RANKINGS OF INSTITUTIONS AND AUTHORS

In this paper we analyse the research in Economics in Spain during the 1990s considering the contributions of both Spanish and foreign economist who have worked in Spain during that period. To do so, we use different bibliometric indicators in order to elaborate rankings for both institutions and researchers. These rankings can be useful for several potentials users such as: a) Evaluation Agencies and Funding Bodies to help them in grant-allocation decisions; b) Graduate students who whish to choose the right institution to complete their postgraduate education, and c) Young Ph Ds who have entered the academic job market and need information about the research perfomance of different institutions.

Microwave Photon Detector in Circuit QED

Quantum optical photodetection has occupied a central role in understanding radiation-matter interactions. It has also contributed to the development of atomic physics and quantum optics, including applications to metrology, spectroscopy, and quantum information processing. The quantum microwave regime, originally explored using cavities and atoms, is seeing a novel boost with the generation of nonclassical propagating fields in circuit quantum electrodynamics (QED). This promising field, involving potential developments in quantum information with microwave photons, suffers from the absence of photodetectors. Here, we design a metamaterial composed of discrete superconducting elements that implements a high-efficiency microwave photon detector. Our design consists of a microwave guide coupled to an array of metastable quantum circuits, whose internal states are irreversibly changed due to the absorption of photons. This proposal can be widely applied to different physical systems and can be generalized to implement a microwave photon counter.Comment: accepted in Phys. Rev. Let

Limits of flexural wave absorption by open lossy resonators: reflection and transmission problems

The limits of flexural wave absorption by open lossy resonators are analytically and numerically reported in this work for both the reflection and transmission problems. An experimental validation for the reflection problem is presented. The reflection and transmission of flexural waves in 1D resonant thin beams are analyzed by means of the transfer matrix method. The hypotheses, on which the analytical model relies, are validated by experimental results. The open lossy resonator, consisting of a finite length beam thinner than the main beam, presents both energy leakage due to the aperture of the resonators to the main beam and inherent losses due to the viscoelastic damping. Wave absorption is found to be limited by the balance between the energy leakage and the inherent losses of the open lossy resonator. The perfect compensation of these two elements is known as the critical coupling condition and can be easily tuned by the geometry of the resonator. On the one hand, the scattering in the reflection problem is represented by the reflection coefficient. A single symmetry of the resonance is used to obtain the critical coupling condition. Therefore the perfect absorption can be obtained in this case. On the other hand, the transmission problem is represented by two eigenvalues of the scattering matrix, representing the symmetric and anti-symmetric parts of the full scattering problem. In the geometry analyzed in this work, only one kind of symmetry can be critically coupled, and therefore, the maximal absorption in the transmission problem is limited to 0.5. The results shown in this work pave the way to the design of resonators for efficient flexural wave absorption

Segregation-induced grain boundary electrical potential in ionic oxide materials: A first principles model

A first principles continuum analytical model for cationic segregation to the grain boundaries in complex ceramic oxides is presented. The model permits one to determine the electric charge density and the segregation-induced electric potential profiles through the grain and can be extrapolated to the range of nanostructured grain sizes. The theoretical predictions are compared with existing data for yttria-stabilized tetragonal zirconia polycrystals. The implications for physical properties (mainly high temperature plasticity and hardening behaviour) are then discussed.Gobierno de España MAT2009-14351-C02-01, MAT2009-14351-C02-0

Cosmological Bianchi Class A models in S\'aez-Ballester theory

We use the S\'aez-Ballester (SB) theory on anisotropic Bianchi Class A cosmological model, with barotropic fluid and cosmological constant, using the Hamilton or Hamilton-Jacobi approach. Contrary to claims in the specialized literature, it is shown that the S\'aez-Ballester theory cannot provide a realistic solution to the dark matter problem of Cosmology for the dust epoch, without a fine tunning because the contribution of the scalar field in this theory is equivalent to a stiff fluid (as can be seen from the energy--momentum tensor for the scalar field), that evolves in a different way as the dust component. To have similar contributions of the scalar component and the dust component implies that their past values were fine tunned. So, we reinterpreting this null result as an indication that dark matter plays a central role in the formation of structures and galaxy evolution, having measureable effects in the cosmic microwave bound radiation, and than this formalism yield to this epoch as primigenius results. We do the mention that this formalism was used recently in the so called K-essence theory applied to dark energy problem, in place to the dark matter problem. Also, we include a quantization procedure of the theory which can be simplified by reinterpreting the theory in the Einstein frame, where the scalar field can be interpreted as part of the matter content of the theory, and exact solutions to the Wheeler-DeWitt equation are found, employing the Bianchi Class A cosmological models.Comment: 24 pages; ISBN: 978-953-307-626-3, InTec

Estudi d'una tècnica analítica per al control de l'estat de conservació de l'avellana

Peer Reviewe

Bright and Gap Solitons in Membrane-Type Acoustic Metamaterials

We study analytically and numerically envelope solitons (bright and gap solitons) in a one-dimensional, nonlinear acoustic metamaterial, composed of an air-filled waveguide periodically loaded by clamped elastic plates. Based on the transmission line approach, we derive a nonlinear dynamical lattice model which, in the continuum approximation, leads to a nonlinear, dispersive and dissipative wave equation. Applying the multiple scales perturbation method, we derive an effective lossy nonlinear Schr\"odinger equation and obtain analytical expressions for bright and gap solitons. We also perform direct numerical simulations to study the dissipation-induced dynamics of the bright and gap solitons. Numerical and analytical results, relying on the analytical approximations and perturbation theory for solions, are found to be in good agreement

Influence of alternating air injection on the color and <em>“alambrado”</em> of natural black olives cv. Arauco, as compared with the traditional Argentine method

Ripe black olives cv. Arauco were processed under different conditions to evaluate the effects of alternating air injection (AI) on the color of olives and on spoilage known as “<em>alambrado</em>”, using a system based on the one patented by the “Instituto de la Grasa” (Sevilla, Spain), as compared with the traditional Argentine processing method, which consists of drying the olives in natural air (“<em>extendido</em>”) for 24 hours at 7, 14 and 21 days of fermentation. Four types of fermentation were used: brine at 2% NaCl plus AI; brine at 2% NaCl plus three “<em>extendidos</em>”; brine at 9% NaCl plus three “<em>extendido</em>s”; and brine at 9% NaCl plus AI and one “<em>extendido</em>”. As previously observed in other varieties by other authors, we noticed that lower pH values were achieved in 2% NaCl fermentations vs. 9% NaCl fermentations. AI prevented the “<em>alambrado</em>” whereas brine at 2% NaCl reduced this spoilage as compared with brine at 9% NaCl. The darkest color of olives was obtained with three “<em>extendido</em>s”, but 83% of brightness reduction was achieved with only one “<em>extendido</em>”. The “<em>extendido</em>” process decreased the texture. We conclude that the combination of AI and “<em>extendido</em>” can add benefits to natural black olives of the Arauco variety.<br><br>Se elaboraron aceitunas negras maduras variedad Arauco en distintas condiciones para evaluar la inyección alternante de aire (IA) con un sistema basado en el patentado por el Instituto de la Grasa, en comparación con la elaboración tradicional argentina donde se realiza exposición al aire en seco (“extendido”) de los frutos durante 24 h, en tres momentos de la fermentación (después de 7, 14 y 21 días). Se hicieron cuatro tipos de fermentaciones: en salmuera al 2% con IA; en salmuera al 2% y 9% con tres “extendidos” y salmuera 9% con IA y un “extendido”. Se alcanzaron los valores mas bajos de pH en fermentaciones con el 2% de NaCl versus las de 9%. La IA evita el defecto de “alambrado” y lo reduce la concentración de 2% versus la de 9%. El color más oscuro se obtiene aplicando el “extendido” en tres oportunidades, pero con una aplicación se alcanza el 83% de la reducción de luminosidad alcanzada por las tres aplicaciones. La textura se ve disminuida por el proceso de “extendido”. La combinación de la IA y el “extendido” reducen el defecto de “alambrado” y oscurecen las aceitunas negras al natural de la variedad Arauco