Multiple photon Hamiltonian in linear quantum optical networks

We give an alternative derivation for the explicit formula of the effective Hamiltonian describing the evolution of the quantum state of any number of photons entering a linear optics multiport. The description is based on the effective Hamiltonian of the optical system for a single photon and comes from relating the evolution in the Lie group that describes the unitary evolution matrices in the Hilbert space of the photon states to the evolution in the Lie algebra of the Hamiltonians for one and multiple photons. We give a few examples of how a group theory approach can shed light on some properties of devices with two input ports.Comment: 6 pages. Comments welcom

Distribución espacio-temporal de los caprélidos (Crustacea: Amphipoda) asociados al alga invasora Asparagopsis armata Harvey en el sur de la Península Ibérica

The caprellid fauna associated to Asparagopsis armata was studied in a spatio- temporal scale at the Southern coast of the Iberian Peninsula. Fourteen stations were selected for the spatial study along the axis Mediterranean-Atlantic and five stations were studied bimonthly (Feb08-Feb09). A gradient of decreasing oxygen and increasing salinity from the Atlantic to the Mediterranean was measured. Eight caprellid species were found: Caprella acanthifera , C. dani- levskii , C. equilibra , C. grandimana , C. hirsuta , C. liparotensis , C. penantis and Pseudoprotella phasma . Caprella penantis and C. liparotensis were the dominant species, and Caprella hirsuta was the most discriminating species between Mediterranean and Atlantic stations, reaching high abundances only in the strictly Mediterranean localities. The seaweed biomass showed higher values in April-June while water temperature was higher in August-October. Maximum caprellid densities were found in April-June (Mediterranean stations) and August-October (Atlantic stations) showing a gradient along the spatial axis. Therefore, optimal seasonal environmental conditions for caprellid cycles are reached sooner in the Mediterranean than in the Atlantic. The number of associated caprellid species in the non-native A.armata is very high when compared with data of other native seaweeds of the Iberian Peninsula and Northern Africa, so the toxic and unpalatable substances of this seaweed do not seem to affect negatively to the caprellid community.Se estudió la fauna de caprélidos asociados a Asparagopsis armata en una escala espacio-temporal en la costa sur de la Península Ibérica Se seleccionaron 14 estaciones para el estudio espacial a lo largo de un eje Mediterráneo-Atlántico, y 5 estaciones se utilizaron para el estudio bimensual desde febrero de 2008 hasta febrero 2009. Se registró un gradiente de disminución de oxígeno y aumento de salinidad desde el Atlántico hacia el Mediterráneo. Se identificaron 8 especies de caprélidos asociados a A. armata : Caprella acanthifera , C. danilevskii , C. equilibra , C. grandimana , C. hirsuta , C. liparotensis , C. penantis y Pseudoprotella phasma . Caprella penantis y C. liparotensis fueron las especies dominantes, y C. hirsuta fue la especie que más discriminó entre estaciones del Mediterráneo y el Atlántico, alcanzando densidades importantes sólo en las estaciones estrictamente mediterráneas. La biomasa del alga mostró los valores más altos en abril-junio mientras que la temperatura del agua fue mayor en agosto-octubre. Las densidades mayores de caprélidos se registraron en abril-junio (estaciones mediterráneas) y agosto-octubre (estaciones atlánticas) mostrando un gradiente a lo largo del eje espacial. Por tanto, las condiciones óptimas para el desarrollo de los caprélidos se alcanzan antes en el Mediterráneo que en el Atlántico. El número de especies de caprélidos asociados al alga no nativa A. armata es muy alto cuando se compara con datos de otras algas nativas de la Península Ibérica y norte de África, de forma que la sustancias tóxicas y poco palatables de este alga parecen no afectar negativamente a la comunidad de caprélidos

Los caprélidos (Crustacea: Amphipoda) del estrecho de Gibraltar y su utilidad como bioindicadores marinos

Los caprélidos son pequeños crustáceos marinos que viven asociados a algas e invertebrados marinos principalmente. Aunque son fundamentales en las redes tróficas marinas y sirven de alimento a muchas especies de peces, han sido muy poco estudiados. El laboratorio de Biología Marina ha desarrollado en los últimos años un estudio exhaustivo de las comunidades de caprélidos del Campo de Gibraltar. Se han descrito 10 especies nuevas para la ciencia y seis nuevas citas para el estrecho de Gibraltar ascendiendo hasta 28 el número de especies conocidas para el Campo de Gibraltar. La mayoría de las especies de caprélidos se han encontrado sobre algas e hidrozoos, aunque algunos se han encontrado asociados al sedimento. En cuanto al modo de alimentación, existen especies filtradoras, depredadoras y depositívoras y se concluye que la estrategia alimentaria está claramente relacionada con el comportamiento de sujección al sustrato (posición erguida versus paralela). Se ha observado canibalismo en la especie Phtisica marina y cuidado parental de los juveniles en Pseudoprotella phasma . Al carecer de fase larvaria planctónica, los caprélidos tienen limitada la capacidad de dispersión. Se ha demostrado también el valor de los caprélidos como bioindicadores; estudiando la comunidad de caprélidos puede conocerse, sin necesidad de realizar costosos análisis fisicoquímicos, la calidad ambiental de las zonas costeras

Validation of close-range photogrammetry for architectural and archaeological heritage Analysis of point density and 3D mesh geometry

The 3D digitization and Building Information Modeling (BIM), which is based on parametric objects, have considerably advanced by developing massive data capture techniques. Thus, reverse engineering currently plays a major role as these technologies capture accurately and efficiently the geometry, color and textures of complex architectural, archaeological and cultural heritage. This paper aims to validate close-range Structure from Motion (SfM) for heritage by analyzing the point density and the 3D mesh geometry in comparison with Terrestrial Laser Scanning (TLS). The accuracy of the results and the geometry mainly depends on the processing performed on the point set. Therefore, these two variables are significant in the 3D reconstruction of heritage buildings. This paper focuses on a 15th century case study in Seville (Spain): the main façade of Casa de Pilatos. Ten SfM surveys were carried out varying the capture method (simple and stereoscopic) and the number of shots, distances, orientation and procedure. A mathematical analysis is proposed to verify the point spatial resolution and the accuracy of the 3D model geometry by section profiles in SfM data. SfM achieved acceptable accuracy levels to generate 3D meshes despite disordered shots and the number of images. Hence, stereoscopic photography using new instruments improved the results of close-range photogrammetry while reducing the required number of photographs

Redescription of Caprella hirsuta Mayer, 1890 (Crustacea, Amphipoda, Caprellidea) from the Strait of Gibraltar

Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen

In-situ disinfection of wastes generated in dwellings by utilizing ozone for their safe incorporation into the recycling chain

The Covid-19 pandemic has certainly changed behaviour patterns in many aspects of life, such as the management of solid wastes inside residential spaces. The goal of this research work is to study an ozone generator device as a disinfection and sterilization tool for these wastes in dwellings themselves, thus re-establishing the selective collection to take them back to the recycling chain. In addition, an approach to the risk verification is made. The methodology is based on an experimentation with a device designed to be as cheap as possible. A room like a bedroom is used as a test bed to apply the device, but with no people inside the room to avoid risks. The results show that the device is feasible, concluding that risks are acceptable if its use is correct and appropriate equipment is available to be applied and controlled, all without prejudice of the rigorous control by the competent authorities that approve its us

Optimal approximation to unitary quantum operators with linear optics

Producción CientíficaLinear optical systems acting on photon number states produce many interesting evolutions, but cannot give all the allowed quantum operations on the input state. Using Toponogov’s theorem from differential geometry, we propose an iterative method that, for any arbitrary quantum operator U acting on n photons in m modes, returns an operator Ũ which can be implemented with linear optics. The approximation method is locally optimal and converges. The resulting operator Ũ can be translated into an experimental optical setup using previous results.Ministerio de Ciencia e Innovación- FEDER (grants PID2020-119418GB-I00 and PID2020-115930GA-I00)Junta de Castilla y León (project VA296P18)Universitat Jaume I (project UJI-B2018- 35 and grant UJI-B2018-10)Ministerio de Asuntos Económicos y Transformación Digital (grant MTM2017-84851-C2-2)Ministerios de Ciencia e Innovación y de Universidades (grant PGC2018-096446-B-C22

Multiple photon effective Hamiltonians in linear quantum optical networks

Producción CientíficaWe give an alternative derivation for the explicit formula of the effective Hamiltonian describing the evolution of the quantum state of any number of photons entering a linear optics multiport. The description is based on the effective Hamiltonian of the optical system for a single photon and comes from relating the evolution in the Lie group that describes the unitary evolution matrices in the Hilbert space of the photon states to the evolution in the Lie algebra of the Hamiltonians for one and multiple photons. Our derivation complements previous results with a point of view which reminds of the Schrödinger picture. These group theory results allow us to prove that quantum optical linear networks obey different proportionality rules which relate the expected photon number at each input and output ports. In particular, we show that for a uniform photon input the average photon number at the output is preserved for any linear multiport.Ministerio de Economía, Industria y Competitividad ( Projects TEC2015-69665-R / MTM2017-84851-C2-2-P / MTM2015-65764-C3-2-P )Junta de Castilla y León (VA089U16)Universitat Jaume I (grants P1-1B2015-02 / P1-B2016-07

Method to determine which quantum operations can be realized with linear optics with a constructive implementation recipe

The evolution of quantum light through linear optical devices can be described by the scattering matrix S of the system. For linear optical systems with m possible modes, the evolution of n input photons is given by a unitary matrix U=φm,M(S), derived from a known homomorphism, φm,M, which depends on the size of the resulting Hilbert space of the possible photon states, M. We present a method to decide whether a given unitary evolution U for n photons in m modes can be achieved with linear optics or not and the inverse transformation φ−1m,M when the transformation can be implemented. Together with previous results, the method can be used to find a simple optical system which implements any quantum operation within the reach of linear optics. The results come from studying the adjoint map between the Lie algebras corresponding to the Lie groups of the relevant unitary matrices