Precision of cavity-enhanced optical rotation measurements

The signal to noise ratio in atomic magnetometry is fundamentally limited by the optical depth of the atomic ensemble. During the last decade, different technics for optical depth enhancement has been developed by several groups, some of them involving the implementation of an optical cavity. This thesis evaluates the performance of such an implementation by the polarization read out noise analysis of an optical cavity with similar characteristics as the already implemented by other groups. We obtained an estimated value for the signal to noise ratio enhancement with a cavity of 814 Finesse, and we studied the behaviour of the different sources of polarization noise in this system

Reducción de la Decoherencia Cuántica en Fotónica Integrada

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de Lectura: 24-03-2023La fotónica cuántica integrada es un elemento indispensable para para la miniaturización, estabilización y escalabilidad de las tecnologías cuánticas. El desarrollo de circuitos fotónicos integrados para aplicación en tecnologías cuánticas ayudará a traspasar el cuello de botella hacia niveles superiores de disponibilidad tecnológica y comercialización. La decoherencia cuántica supone uno de los retos técnicos a nivel fundamental con mayor relevancia para la realización de este desarrollo. En este contexto, el objetivo de este proyecto ha sido el de proporcionar herramientas teóricas para orientar la conceptualización y el diseño de los bloques fundamentales de los circuitos cuánticos integrados con vistas a la reducción de la decoherencia cuántica en estos sistemas. Los resultados obtenidos en forma de modelos teóricos, métodos numéricos de simulación y esquemas de optimización facilitan estas herramientas a través una serie de nuevos instrumentos matemáticos que sirven tanto para la caracterización de la decoherencia en diferentes componentes como para guías de diseño para su reducción: Expresiones analíticas que relacionan directamente los parámetros de diseño de estructuras fotónicas con el grado de decoherencia de la plataforma; Modelos para la simulación numérica de emisores cuánticos integrados en estructuras fotónicas que conectan la variación de los parámetros del diseño con el impacto en las figuras de mérito que caracterizan la decoherencia; Esquemas de optimización basados en métodos de Machine Learning para estructuras de fotónica cuántica integrada que ofrecen una reducción sin precedentes en términos de consumo de recursos computacionales; Interpretaciones físicas de las soluciones de los modelos desarrollados que contribuyen al avance del conocimiento del comportamiento de componentes de circuito en diferentes condiciones. El aparato matemático desarrollado ha sido evaluado a través de su aplicación en diferentes casos prácticos validando su fiabilidad y demostrando resultados prometedores: Identificación de los valores de los parámetros de diseño necesarios para la maximización de la indistinguibilidad y la eficiencia de extracción en emisores cuánticos acoplados a guías de onda dependiendo de las características del emisor, estimando incrementos en la indistinguibilidad de hasta un 30% para diseños optimizados; Optimización del diseño de una cavidad óptica para integración en chip de emisores cuánticos que garantiza valores de indistinguibilidad y eficiencia de extracción cercanos a la unidad con emisores fuertemente disipativos a temperatura ambiente; Relajación de los requisitos técnicos generales para cavidades ópticas a partir de una nueva plataforma propuesta basada en la integración de clústeres de emisores cuánticos acoplados que garantiza indistinguibilidad perfecta con emisores fuertemente disipativos a temperatura ambiente para las configuraciones óptimas. Esperamos que los resultados obtenidos en esta disertación contribuyan al avance del conocimiento para el desarrollo de la fotónica cuántica integrada y sirvan de hoja de ruta para la realización de nuevas demostraciones experimentales que incrementen su impacto en el estado del arte de las tecnologías cuántica

Unsuspected and extensive transmission of a drug-susceptible Mycobacterium tuberculosis strain

<p>Abstract</p> <p>Background</p> <p>A large and unsuspected tuberculosis outbreak involving 18.7% of the total of the tuberculosis cases studied, was detected in a population-based molecular epidemiological study performed in Zaragoza (Spain) from 2001 to 2004.</p> <p>Methods</p> <p>The <it>Mycobacterium tuberculosis </it>drug-susceptible strain, named <it>MTZ </it>strain, was genetically characterized by IS<it>6110</it>-RFLP, Spoligotyping and by MIRU-VNTR typing and the genetic patterns obtained were compared with those included in international databases. The characteristics of the affected patients, in an attempt to understand why the <it>MTZ </it>strain was so highly transmitted among the population were also analyzed.</p> <p>Results</p> <p>The genetic profile of the <it>MTZ </it>strain was rare and not widely distributed in our area or elsewhere. The patients affected did not show any notable risk factor for TB.</p> <p>Conclusion</p> <p>The <it>M. tuberculosis </it>strain <it>MTZ</it>, might have particular transmissibility or virulence properties, and we believe that greater focus should be placed on stopping its widespread dissemination.</p

La transformación digital: un aliado estratégico en la era COVID

The pandemic of coronavirus SARS-CoV-2 is acting as a catalyst for change within organizations: they are moving, creating, and innovating. They do so in hopes of improving performance and efficiency, much needed qualities to overcome this challenging period. Digital transformation (usually mistaken for ‘digitalization’) has emerged as a sure bet that can save many small and big corporations. At the same time, it is progressively becoming a strategic ally for technological efficiency within the organization, allowing a reduction of costs and an increase of benefits. Nonetheless, these improvements are not only found in the private sector, but they can also be used to facilitate the relationship between citizens and administrations. The European Union might act as a promoting and unifying figure in this digital transformation of member states. However, easy in theory, the practical world needs: time, leaders, and proper financing.La pandemia provocada por el coronavirus SARS-CoV-2 está actuando como combustible en las organizaciones para que se muevan, creen e innoven. De esta forma, pretenden mejorar sus rendimientos y ser más eficientes para superar el actual periodo de crisis. La transformación digital, muchas veces confundida con digitalización, surge como un caballo ganador que puede suponer una tabla de salvación para muchas corporaciones grandes o pequeñas. A su vez, se está convirtiendo en un aliado estratégico al aplicar de forma eficaz la tecnología en los procesos de trabajo y, con ello, reducir costes, agilizar estructuras y mejorar los beneficios. Estas mejoras no solo se reducen al ámbito privado, sino también a lo público, al facilitar al ciudadano la tramitación que debe realizar con las distintas administraciones. La Unión Europea puede actuar como impulsor y unificador de esta transformación digital de los Estados miembros. Sin embargo, su implantación no es un camino tan llano como pudiera parecer y exige tiempo, liderazgo y financiación

Precision of cavity-enhanced optical rotation measurements

The signal to noise ratio in atomic magnetometry is fundamentally limited by the optical depth of the atomic ensemble. During the last decade, different technics for optical depth enhancement has been developed by several groups, some of them involving the implementation of an optical cavity. This thesis evaluates the performance of such an implementation by the polarization read out noise analysis of an optical cavity with similar characteristics as the already implemented by other groups. We obtained an estimated value for the signal to noise ratio enhancement with a cavity of 814 Finesse, and we studied the behaviour of the different sources of polarization noise in this system

El teletrabajo en la era COVID

Teleworking was one of the main reasons as to why many companies and public institutions were able to keep their economic activity during the spring lockdown caused by the SARS-CoV-2 Coronavirus pandemic. Teleworking is been used as a way of responding to the uncertainty provoked by the new summer outbreaks of COVID-19. This technique of working presents many advantages and certain disadvantages. However, if the advantages prevail, entities can overcome its challenges, and conceptual changes are addressed, it will probably be implemented in most institutions whose activity allows this new style of working. Teleworking has arrived to stay.El teletrabajo fue un elemento principal para que muchas organizaciones e instituciones mantuvieran su actividad económica durante el confinamiento de primavera provocados por la pandemia del coronavirus SARS-CoV-2. La desescalada y el periodo posterior en verano mantienen en la actualidad índices elevados de trabajo a distancia como respuesta a la incertidumbre que provocan los continuos rebrotes de COVID-19. El trabajo en remoto presenta sus ventajas e inconvenientes, pero en la medida que las primeras prevalezcan sobre las segundas, y que las organizaciones superen los retos y cambios de mentalidad necesarios, será probablemente implantado en una mayoría de organizaciones cuya actividad lo permita. El teletrabajo ha venido para quedarse

Photonic and Thermal Modelling of Microrings in Silicon, Diamond and GaN for Temperature Sensing

© 2020 by the authors.Staying in control of delicate processes in the evermore emerging field of micro, nano and quantum-technologies requires suitable devices to measure temperature and temperature flows with high thermal and spatial resolution. In this work, we design optical microring resonators (ORRs) made of different materials (silicon, diamond and gallium nitride) and simulate their temperature behavior using several finite-element methods. We predict the resonance frequencies of the designed devices and their temperature-induced shift (16.8 pm K−1 for diamond, 68.2 pm K−1 for silicon and 30.4 pm K−1 for GaN). In addition, the influence of two-photon-absorption (TPA) and the associated self-heating on the accuracy of the temperature measurement is analysed. The results show that owing to the absence of intrinsic TPA-processes self-heating at resonance is less critical in diamond and GaN than in silicon, with the threshold intensity Ith=α/β , α and β being the linear and quadratic absorption coefficients, respectively.Research funded by European Association of National Metrology Institutes (JRP f14 PhotOQuanT—17FUN05). This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme. The authors gratefully acknowledge support by the DFG research training group GrK1952/1 “Metrology for Complex Nanosystems”.Peer reviewe

Enhancement of the indistinguishability of single photon emitters coupled to photonic waveguides

One of the main steps towards large-scale quantum photonics consists of the integration of single photon sources (SPS) with photonic integrated circuits (PICs). For that purpose, the PICs should offer an efficient light coupling and a high preservation of the indistinguishability of photons. Therefore, optimization of the indistinguishability through waveguide design is especially relevant. In this work we have developed an analytical model that uses the Green's Dyadic of a 3D unbounded rectangular waveguide to calculate the coupling and the indistinguishability of an ideal point-source quantum emitter coupled to a photonic waveguide depending on its orientation and position. The model has been numerically evaluated through finite-difference time-domain (FDTD) simulations showing consistent results. The maximum coupling is achieved when the emitter is embedded in the center of the waveguide but somewhat surprisingly the maximum indistinguishability appears when the emitter is placed at the edge of the waveguide where the electric field is stronger due to the surface discontinuity.Horizon 2020 Framework Programme (820423)

Perfect Photon Indistinguishability from a Set of Dissipative Quantum Emitters

Single photon sources (SPS) based on semiconductor quantum dot (QD) platforms are restricted to low temperature (T) operation due to the presence of strong dephasing processes. Although the integration of QD in optical cavities provides an enhancement of its emission properties, the technical requirements for maintaining high indistinguishability (I) at high T are still beyond the state of the art. Recently, new theoretical approaches have shown promising results by implementing two-dipole-coupled-emitter systems. Here, we propose a platform based on an optimized five-dipole-coupled-emitter system coupled to a cavity which enables perfect I at high T. Within our scheme the realization of perfect I single photon emission with dissipative QDs is possible using well established photonic platforms. For the optimization procedure we have developed a novel machine-learning approach which provides a significant computational-time reduction for high demanding optimization algorithms. Our strategy opens up interesting possibilities for the optimization of different photonic structures for quantum information applications, such as the reduction of quantum decoherence in clusters of coupled two-level quantum systems.European Union’s Horizon 2020 research and innovation program under grant agreement No. 820423 (S2QUIP); CSIC Quantum Technology Platform PT-001y Agencia Estatal de Investigación (AEI) grant PID2019-106088RB-C31; European Metrology Programme for Innovation and Research: 20FUN05 SEQUME and CSIC Interdisciplinary Thematic Platform (PTI+): PTI-QTEP+

Epidemiología descriptiva de meningitis no meningocócicas bacterianas de la provincia de Zaragoza (1999-2004): evaluación de su sistema de vigilancia Descriptive epidemiology of non-meningococcal bacterial meningitis in the province of Saragossa [Spain] from 1999 to 2004: evaluation of the Epidemiological Surveillance System

Objetivos: Describir las meningitis no meningocócicas bacterianas (MnMB) y evaluar el Sistema de Vigilancia Epidemiológica (SVE) en la provincia de Zaragoza entre 1999 y 2004. Métodos: Se utilizó el registro de enfermedades de declaración obligatoria (EDO) y el conjunto mínimo básico de datos (CMBD). Se evaluó el SVE utilizando criterios de los Centers for Disease Control and Prevention, estimando la exhaustividad mediante captura-recaptura. Resultados: Se notificaron 111 casos de MnMB (62,2% en hombres). La edad media fue de 40,7 años. La mayor proporción de casos (16,5%) fue en niños menores de 2 años. La forma clínica en el 81,1% de los casos fue la meningitis; el 70,3% fue diagnosticada por cultivo. Aparecieron Streptococcus en el 54% de los casos (el 82% por S. pneumoniae), enterobacterias en el 5,4%, Lysteria y Staphylococcus en el 4,5%, Pseudomona aeruginosa en el 1,8%, y Haemophilus influenzae en el 0,9%. La incidencia por 100.000 habitantes fue entre 1,6 en 2004 y 2,6 en 2001. La letalidad fue del 7,3%. La exhaustividad del sistema EDO fue máxima en el año 2001 (del 84,4%). La exhaustividad conjunta con CMBD fue superior al 85% y la oportunidad fue de 2 días. La aceptabilidad del sistema fue buena, ya que el 75% de las variables estaban cumplimentadas en el 97% de las encuestas. Conclusiones: Se destaca la relevancia de la evaluación del SVE en función de sus resultados. Las MnMB debidas a S. pneumoniae representan un grupo significativo y su letalidad es elevada. La exhaustividad del SVE en Zaragoza supera el 80%, al considerar EDO y CMBD. La incorporación del CMBD en la vigilancia facilitaría una aproximación a la incidencia real de algunas EDO.<br>Objectives: To describe non-meningococcal bacterial meningitis (nMM) and to evaluate the Epidemiological Surveillance System (ESS) in the province of Saragossa (Spain) between 1999 and 2004. Methods: Information was obtained from the register of diseases subject to mandatory reporting and the Minimum Basic Data Set (MBDS). The ESS was evaluated by using the Centers for Disease Control and Prevention (CDC) criteria and by estimating the completeness of the system through the capture-recapture technique. Results: 111 cases of nMM were notified (62.2% in males) and the mean age was 40.7 years. The largest proportion of cases (16.5%) occurred in children under 2 years of age. The clinical presentation was meningitis in 81.1%. Diagnosis was through bacterial culture in 70.3%. Streptococcus sp. was found in 54% (82% due to S. pneumoniae), enterobacteria in 5.4%, Listeria and Staphylococcus in 4.5%, Pseudomonas aeruginosa in 1.8%, and Haemophilus influenzae in 0.9%. The incidence rate per 100,000 inhabitants was 1.6 in 2004 and 2.6 in 2001. The case fatality was 7.3%. The completeness of the mandatory reporting system reached a peak in 2004 at 84.4%. The combined completeness of the MBDS and the mandatory reporting system was above 85% and timeliness of reporting was 2 days. The acceptability of the system was high since 75% of all variables were complete in 97% of the questionnaires. Conclusion: We highlight the importance of evaluation of the ESS, based on its results. nMM due to S. pneumoniae represent an important group of diseases and their case fatality is high. The completeness of the ESS in Saragossa was over 80% when the mandatory reporting system and the MBDS were combined. Incorporating the MBDS into surveillance would facilitate the estimation of the incidence of various diseases subject to mandatory reporting