Remote Preparation of Single-Photon "Hybrid" Entangled and Vector-Polarization States

Quantum teleportation faces increasingly demanding requirements for transmitting large or even entangled systems. However, knowledge of the state to be transmitted eases its reconstruction, resulting in a protocol known as remote state preparation. A number of experimental demonstrations to date have been restricted to single-qubit systems. We report the remote preparation of two-qubit "hybrid" entangled states, including a family of vector-polarization beams. Our single-photon states are encoded in the photon spin and orbital angular momentum. We reconstruct the states by spin-orbit state tomography and transverse polarization tomography. The high fidelities achieved for the vector-polarization states opens the door to optimal coupling of down-converted photons to other physical systems, such as an atom, as required for scalable quantum networks, or plasmons in photonic nanostructures.Comment: Letter: 4 pages, 1 figure. Supplementary material: 1 pag

Generation of Hyperentangled Photons Pairs

We experimentally demonstrate the first quantum system entangled in every degree of freedom (hyperentangled). Using pairs of photons produced in spontaneous parametric downconversion, we verify entanglement by observing a Bell-type inequality violation in each degree of freedom: polarization, spatial mode and time-energy. We also produce and characterize maximally hyperentangled states and novel states simultaneously exhibiting both quantum and classical correlations. Finally, we report the tomography of a 2x2x3x3 system (36-dimensional Hilbert space), which we believe is the first reported photonic entangled system of this size to be so characterized.Comment: 5 pages, 3 figures, 1 table, published versio

Arbitraje y justicia ordinaria. Los arbitrajes compromisarios en Derecho Romano

[Resumen] La investigación trata del primer reconocimiento oficial del arbitraje por parte del derecho pretorio en el período romano-republicano y de la elaboración de su régimen jurídico por parte de la Jurisprudencia de la época del Principado. Se analiza la base negocial de los arbitrajes, constituida por el compromissum y el receptum arbitrii, las peculiaridades del procedimiento en relación con la legalidad procesal civil y los efectos de la sentencia arbitral.[Abstract] This paper deals with the first official recognition of arbitration proceedings by the Pretorian Law during the Roman-Republican times, and with the elaboration of its set of rules, by the case-Iaw during the Principality. It’s analyzed the agreed basis of arbitration, made up by the compromissum and the receptum arbitrii, the proceedings particularities in relation to the civil procédural legality and the effects of the arbitral awar

Measurement of geometric phase for mixed states using single photon interferometry

Geometric phase may enable inherently fault-tolerant quantum computation. However, due to potential decoherence effects, it is important to understand how such phases arise for {\it mixed} input states. We report the first experiment to measure mixed-state geometric phases in optics, using a Mach-Zehnder interferometer, and polarization mixed states that are produced in two different ways: decohering pure states with birefringent elements; and producing a nonmaximally entangled state of two photons and tracing over one of them, a form of remote state preparation.Comment: To appear in Phys. Rev. Lett. 4 pages, 3 figure

Hyperentangled Bell-state analysis

It is known that it is impossible to unambiguously distinguish the four Bell states encoded in pairs of photon polarizations using only linear optics. However, hyperentanglement, the simultaneous entanglement in more than one degree of freedom, has been shown to assist the complete Bell analysis of the four Bell states (given a fixed state of the other degrees of freedom). Yet introducing other degrees of freedom also enlarges the total number of Bell-like states. We investigate the limits for unambiguously distinguishing these Bell-like states. In particular, when the additional degree of freedom is qubit-like, we find that the optimal one-shot discrimination schemes are to group the 16 states into 7 distinguishable classes, and that an unambiguous discrimination is possible with two identical copies.Comment: typos corrected, to appear in PRA, 5 pages, 2 figures, 2 table

Review of Ship Energy Efficiency

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Energy efficiency has become increasingly relevant in the current economic and environmental situations. This paper aims to create a map of the state of the art of the energy efficiency on the marine sector, both in the scale of the individual ships and the entire industry. The first point of interest will be an examination of the regulatory framework of the shipping sector in regards of energy efficiency. Next there are the procedures implemented on ships with the aim of diminishing their consumption and emissions. These measures range from modifications of the design to the operational practices. Following that will be the potential advances that the industry could implement on a bigger scale to enhance the efficiency of the whole sector. Finally, an overview of the main obstacles for the implementation of these measures will be examined. While the current standards are a temporary solution and several of the most prominent improvements require further investigation, the continuous effort increases the potential of this sector for optimization. These factors emphasize the utility of this review as an introduction to help other studies have a solid understanding of the state of the art of energy efficiency in the naval industry.Xunta de Galicia; ED481A 2021/312Xunta de Galicia; ED431C 2021/3

Flow cytometric analysis of the encystment process induced by paraquat exposure in Haematococcus pluvialis (Chlorophyceae)

The freshwater microalga Haematococcus pluvialis exhibits a unique morphological response to environmental stress, accumulating carotenoid pigment during encystment. The complexity of characterizing the different cell stages and monitoring the pigment cell content during the life cycle of this microalga is one of the main problems reported when assessing astaxanthin accumulation and degradation. Therefore, with the aim of studying the potential encystment response in this microalga by means of flow cytometry (FCM), we induced oxidative stress in cultures of vegetative growing cells by treating them with paraquat, a known generator of superoxide anion radicals. Two flow cytometric approaches were successfully used to monitor the effect of oxidative stress on morphological changes and genesis of carotenoids in H. pluvialis: (1) a cytometric characterization of different cell types based on analysis of the fluorescence of chlorophyll a vs the fluorescence of astaxanthin, and (2) staining with the fluorochromes hydroethidium (HE) and dihydrorhodamine 123 (DHR), in order to measure the in vivo intracellular levels of reactive oxygen species (ROS). FCM data showed that astaxanthin accumulation during encystment hampers the production of ROS. Furthermore, the cell content of astaxanthin seems to be a good indicator of the extent to which H. pluvialis cells undergo oxidative stress, and also of how the cells defend themselves under stress conditions.Xunta de Galicia; INCITE08ENA103032E

Indicadores para la valoración de los resultados de la política macroeconómica de los gobiernos : una aplicación al caso de la economía española (1978-2014)

[Resumen] El presente trabajo tiene como cometido fundamental el análisis para el caso español, de los indicadores sintéticos de resultados macroeconómicos denominados misery-index, propuestos por Arthur Okun y Robert Barro, cuyo objeto principal es medir el desempeño económico de un determinado gobierno y la situación en la que se halla una economía. Este trabajo se organiza del siguiente modo: inicialmente, se realiza una breve exposición sobre los principales objetivos de la política económica, obteniendo indicadores que nos permitan evaluar el nivel de consecución de los objetivos propuestos; seguidamente, se analiza la construcción de indicadores sintéticos de resultados macroeconómicos y se lleva a cabo una propuesta de agregación de determinantes macroeconómicos; a continuación se resumen los usos y aplicaciones del misery-index; por último se efectúa una valoración de los resultados macroeconómicos de los gobiernos en España y se cuantifica la relación existente entre los misery-index y el ciclo económico. Se concluye que el misery-index se muestra como un indicador válido a la hora de calificar la actuación económica de un determinado gobierno; sin embargo, se ha de prestar atención al hecho de que la correlación entre el misery-index y el ciclo económico es ciertamente moderada.[Abstract] This work has a main purpose the analysis for the Spanish case, the synthetic indicators of macroeconomic performance called misery-index proposed by Arthur Okun and Robert Barro, whose main purpose is to measure the economic performance of a given government and the situation in which an economy is. This paper is organized as follows: initially, a brief summary of the main objectives of economic policy is carried, obtaining indicators that allow us to assess the level of achievement of the given objectives; then the construction of synthetic indicators of macroeconomic performance is analized and a proposal macroeconomic determinants aggregation is performed; then the uses and applications of misery-index summarized; finally an assessment of the macroeconomic performance of governments in Spain is carried out and the relationship between misery-index and the economic cycle is quantified. We conclude that the misery-index is displayed as a valid indicator when classifying the economic performance of a Government; however, attention must be focused on the fact that the correlation between the misery-index and the economic cycle is certainly moderate.Traballo fin de grao (UDC.ECO). ADE. Curso 2014/201