Observation of spectral interference for any path difference in an interferometer

We report the experimental observation of spectral interference in a Michelson interferometer, regardless of the relationship between the temporal path difference introduced between the arms of the interferometer and the spectral width of the input pulse. This observation is possible by introducing the polarization degree of freedom into a Michelson interferometer using a typical weak value amplification scenario.Comment: 4 pages, 4 figure

Weak value amplification: a view from quantum estimation theory that highlights what it is and what isn't

Weak value amplification (WVA) is a concept that has been extensively used in a myriad of applications with the aim of rendering measurable tiny changes of a variable of interest. In spite of this, there is still an on-going debate about its true nature and whether is really needed for achieving high sensitivity. Here we aim at solving the puzzle, using some basic concepts from quantum estimation theory, highlighting what the use of the WVA concept can offer and what it can not. While WVA cannot be used to go beyond some fundamental sensitivity limits that arise from considering the full nature of the quantum states, WVA can notwithstanding enhance the sensitivity of real detection schemes that are limited by many other things apart from the quantum nature of the states involved, i.e. technical noise. Importantly, it can do that in a straightforward and easily accessible manner.Comment: 2 pages, 5 figure

How to automate a kinematic mount using a 3D printed Arduino-based system

We demonstrate a simple, flexible and cost-effective system to automatize most of the kinematic mounts available nowadays on the market. It combines 3D printed components, an Arduino board, stepper motors, and simple electronics. The system developed can control independently and simultaneously up to ten stepper motors using commands sent through the serial port, and it is suitable for applications where optical realignment using flat mirrors is required on a periodic basis.Comment: 9 pages, 8 figure

A 3D Printed Toolbox for Opto-Mechanical Components

Nowadays is very common to find headlines in the media where it is stated that 3D printing is a technology called to change our lives in the near future. For many authors, we are living in times of a third industrial revolution. Howerver, we are currently in a stage of development where the use of 3D printing is advantageous over other manufacturing technologies only in rare scenarios. Fortunately, scientific research is one of them. Here we present the development of a set of opto-mechanical components that can be built easily using a 3D printer based on Fused Filament Fabrication (FFF) and parts that can be found on any hardware store. The components of the set presented here are highly customizable, low-cost, require a short time to be fabricated and offer a performance that compares favorably with respect to low-end commercial alternatives.Comment: 9 pages, 9 figure

Optical sectioning in induced coherence tomography with frequency-entangled photons

We demonstrate a different scheme to perform optical sectioning of a sample based on the concept of induced coherence [Zou et al., Phys. Rev. Lett. 67, 318 (1991)]. This can be viewed as a different type of optical coherence tomography scheme where the varying reflectivity of the sample along the direction of propagation of an optical beam translates into changes of the degree of first-order coherence between two beams. As a practical advantage the scheme allows probing the sample with one wavelength and measuring photons with another wavelength. In a bio-imaging scenario, this would result in a deeper penetration into the sample because of probing with longer wavelengths, while still using the optimum wavelength for detection. The scheme proposed here could achieve submicron axial resolution by making use of nonlinear parametric sources with broad spectral bandwidth emission.Comment: Published version. 11 pages, 9 figure

Tunable beam displacer

We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.Comment: 3 pages, 2 figure

Las redes sociales y los SIG como herramientas para conocer las preferencias sociales en las ciudades turísticas: el caso de Benidorm

El auge de las redes sociales como lugar de encuentro virtual ha traído consigo nuevas formas de interacción ciudadana. Éstas, a su vez, han trascendido a una escala espacio-temporal tal que su estudio resulta difícilmente abarcable por métodos tradicionales. A partir de las relaciones que acontecen en línea, las redes sociales recogen una gran cantidad de datos que se actualizan en tiempo real. Así, el objetivo de esta investigación se basa en utilizar estos datos, a modo de muestra representativa, para identificar las preferencias sociales en relación a los espacios de las ciudades turísticas. Se plantea como estudio de caso la ciudad de Benidorm por ser ésta la ciudad turística por excelencia de la provincia de Alicante, con una importante proyección internacional. La metodología consta de tres fases: primero, una aplicación informática obtiene datos de las redes sociales: Foursquare y Twitter; a continuación, los datos son clasificados para que, por último, sean georreferenciados y grafiados en una cartografía para visualizar y evaluar los resultados. Una vez representada la información es posible determinar, por un lado, qué ámbitos de la ciudad de Benidorm adquieren relevancia por ser lugares de concurrencia ciudadana y a partir de los cuales se establece comunicación e intercambio social; y, por otro lado, dar lectura al carácter turístico de la ciudad identificando el tipo y género al que pertenecen sus lugares de interés. La utilización de estas herramientas posibilita la interpretación de los flujos sociales que se producen en el espacio urbano y secunda el planteamiento de estrategias de planificación y gestión, particularmente en el ámbito turístico

La crisis de la ciencia política desde el enfoque de estudio de César Cansino

Las ciencias sociales en general estan en crisis, al igual que las ciencias duras y las humanidades, en este ensayo se centra en la ciencia política y su crisis epistemológica, explicando el enfoque del autor Cesar Cansino