Nonlinear quantum optics in the (ultra)strong light-matter coupling

The propagation of $N$ photons in one dimensional waveguides coupled to $M$ qubits is discussed, both in the strong and ultrastrong qubit-waveguide coupling. Special emphasis is placed on the characterisation of the nonlinear response and its linear limit for the scattered photons as a function of $N$, $M$, qubit inter distance and light-matter coupling. The quantum evolution is numerically solved via the Matrix Product States technique. Both the time evolution for the field and qubits is computed. The nonlinear character (as a function of $N/M$) depends on the computed observable. While perfect reflection is obtained for $N/M \cong 1$, photon-photon correlations are still resolved for ratios $N/M= 2/20$. Inter-qubit distance enhances the nonlinear response. Moving to the ultrastrong coupling regime, we observe that inelastic processes are \emph{robust} against the number of qubits and that the qubit-qubit interaction mediated by the photons is qualitatively modified. The theory developed in this work modelises experiments in circuit QED, photonic crystals and dielectric waveguides.Comment: Comments are wellcom

Scattering in the ultrastrong regime: nonlinear optics with one photon

The scattering of a flying photon by a two-level system ultrastrongly coupled to a one-dimensional photonic waveguide is studied numerically. The photonic medium is modeled as an array of coupled cavities and the whole system is analyzed beyond the rotating wave approximation using Matrix Product States. It is found that the scattering is strongly influenced by the single- and multi-photon dressed bound states present in the system. In the ultrastrong coupling regime a new channel for inelastic scattering appears, where an incident photon deposits energy into the qubit, exciting a photon-bound state, and escaping with a lower frequency. This single-photon nonlinear frequency conversion process can reach up to 50\% efficiency. Other remarkable features in the scattering induced by counter-rotating terms are a blueshift of the reflection resonance and a Fano resonance due to long-lived excited statesComment: 5+4 page

One- and two-photon scattering from generalized V-type atoms

The one- and two-photon scattering matrix S is obtained analytically for a one-dimensional waveguide and a point-like scatterer with N excited levels (generalized V -type atom). We argue that the two-photon scattering matrix contains sufficient information to distinguish between different level structures which are equivalent for single-photon scattering, such as a V -atom with N = 2 excited levels and two two-level systems. In particular, we show that the scattering with the V -type atom exhibits a destructive interference effect leading to two-photon Coupled-Resonator-Induced Transparency, where the nonlinear part of the two-photon scattering matrix vanishes when each incident photon fulfills a single-photon condition for transparency

Single photons by quenching the vacuum

Heisenberg's uncertainty principle implies that the quantum vacuum is not empty but fluctuates. These fluctuations can be converted into radiation through nonadiabatic changes in the Hamiltonian. Here, we discuss how to control this vacuum radiation, engineering a single-photon emitter out of a two-level system (2LS) ultrastrongly coupled to a finite-band waveguide in a vacuum state. More precisely, we show the 2LS nonlinearity shapes the vacuum radiation into a nonGaussian superposition of even and odd cat states. When the 2LS bare frequency lays within the band gaps, this emission can be well approximated by individual photons. This picture is confirmed by a characterization of the ground and bound states, and a study of the dynamics with matrix product states and polaron Hamiltonian methods.Comment: 9 pages, 10 figure

Ranking of palliative care development in the countries of the European Union

Context There is growing interest in monitoring palliative care (PC) development internationally. One aspect of this is the ranking of such development for comparative purposes. Objectives To generate a ranking classification and to compare scores for PC development in the countries of the European Union (EU), 2007 and 2013. PC “development” in this study is understood as a combination of the existence of relevant services in a country (“resources”) plus the capacity to develop further resources in the future (“vitality”). Methods “Resources” comprise indicators of three types of PC services per population (inpatient palliative care units and inpatient hospices [IPCU], hospital support teams [HST] and home care teams [HCT]). “Vitality” of PC is estimated by numerical scores for the existence of a national association, a directory of services, physician accreditation, attendances at a key European conference and volume of publications on PC development. The leading country (by raw score) is then considered as the reference point against which all other countries are measured. Different weightings are applied to resources (75%) and vitality (25%). From this, an overall ranking is constructed. Results The U.K. achieved the highest level of development (86% of the maximum possible score), followed by Belgium and The Netherlands (81%), and Sweden (80%). In the domain resources, Luxembourg, the U.K. and Belgium were leading. The top countries in vitality were Germany and the U.K. In comparison to 2007, The Netherlands, Malta and Portugal showed the biggest improvements, whereas the positions of Spain, France and Greece deteriorated. Conclusion The ranking method permitted a comparison of palliative care development between countries and shows changes over time. Recommendations for improving the ranking include improvements to the methodology and greater explanation of the levels and changes it reveals

Emergent Causality and the N-photon Scattering Matrix in Waveguide QED

In this work we discuss the emergence of approximate causality in a general setup from waveguide QED -i.e. a one-dimensional propagating field interacting with a scatterer. We prove that this emergent causality translates into a structure for the N-photon scattering matrix. Our work builds on the derivation of a Lieb-Robinson-type bound for continuous models and for all coupling strengths, as well as on several intermediate results, of which we highlight (i) the asymptotic independence of space-like separated wave packets, (ii) the proper definition of input and output scattering states, and (iii) the characterization of the ground state and correlations in the model. We illustrate our formal results by analyzing the two-photon scattering from a quantum impurity in the ultrastrong coupling regime, verifying the cluster decomposition and ground-state nature. Besides, we generalize the cluster decomposition if inelastic or Raman scattering occurs, finding the structure of the S-matrix in momentum space for linear dispersion relations. In this case, we compute the decay of the fluorescence (photon-photon correlations) caused by this S-matrix

Torque distribution strategy for a four In-wheel fully electric car

Jornadas de Automática, 2 - 4 de septiembre de 2015. BilbaoElectromobility promises to have a strong impact in several aspects of our life: introducing new means of transport concepts, proposing new business models and allowing to create new vehicle configurations impossible with traditional combustion engines. Regarding the latter, this paper presents a novel torque distribution strategy for a 4 in-wheel electric vehicle which aims to reduce the total longitudinal slip. The control strategy is designed off-line supported by a simulator and tested both in simulation (with a different model from the used for designing) as well as on a real sized prototype. The results show that the total longitudinal slip is successfully reduced after applying the control strategy and additionally, the radius described by the vehicle while cornering is slightly closer to the theoretical Ackerman radius.Ministerio de Economía y Competitividad DPI2013-46912-C2-

One-dimensional few-photon scattering: numerical and analytical techniques

En esta tesis hemos estudiado scattering de pocos fotones en electrodinámica cuántica en guías de onda, donde los fotones se propagan a través de un medio unidimensional interaccionando con algunos scatterers, tales como átomos de dos niveles. Hemos aplicado por primera vez la técnica numérica estados producto de matriz (MPS, por sus siglas en inglés) a este campo. Hemos utilizado métodos analíticos ya conocidos, tales como el formalismo input-output. Hemos caracterizado el espectro de estos modelos, tanto en la aproximación de onda rotatoria (RWA, por sus siglas en inglés) como en el régimen de acoplo ultrafuerte. Estos espectros contienen estados ligados, en los cuales algunas excitaciones fotónicas están confinadas en torno a los scatterers. Hemos estudiado el efecto de estos estados en el decaimiento espontáneo de un átomo de dos niveles en la RWA. Hemos determinado algunas propiedades analíticas de la matriz de scattering. El principio de descomposición de cluster, el cual se da en teoría cuántica de campos al ser esta una teoría relativista, también se da en nuestro caso, pese a estar tratando con modelos no relativistas. Hemos generalizado el principio de cluster a scatterers con memoria, encontrando la estructura de la matriz de scattering compatible con esta generalización. Hemos estudiado scattering en sistemas en los que las ecuaciones de Heisenberg son lineales en los operadores. La matriz de scattering en estos sistemas no induce correlaciones y que ni creación ni aniquilación de partículas están permitidas. Confirmamos estos resultados con varias simulaciones usando MPS. Hemos encontrado una supresión de los efectos no lineales del scattering cuando los scatterers tienden a ser lineales. Hemos estudiado varios problemas de scattering de pocos fotones utilizando los métodos introducidos en la tesis. Hemos caracterizado por completo el scattering de un fotón a través de un átomo de dos niveles en el régimen de acoplo ultrafuerte, donde hemos encontrado que scattering inelástico determinista es posible. Hemos hallado generación de dos fotones también determinista en el scattering de un fotón a través de un átomo cíclico de tres niveles. El scattering de uno y dos fotones a través de un átomo V generalizado ha sido tratado, donde podemos tener transmisión perfecta en ambos casos. La posibilidad de implementar una puerta cuántica de fase de dos qubits se ha considerado usando scattering de dos fotones con paquetes de onda no monocromáticas a través de varios scatterers puntuales; desafortunadamente, pese a que el proceso es posible, la eficiencia es demasiado baja. Finalmente, hemos estudiado los efectos de la distancia entre qubits en el scattering de dos fotones.In this thesis, we have studied few-photon scattering in waveguide quantum electrodynamics (waveguide QED), where photons propagate through a onedimensional medium interacting with some scatterers, such as two-level atoms. The methods we use to tackle these problems are explained in Chap. 2. We have applied for the first time the numerical technique of matrix-product states (MPS) to this field. Besides, we have used previously known analytical methods, such as the input-output formalism. We have characterized the spectrum of archetypical models of waveguide QED in Chap. 3, both in the rotating-wave approximation (RWA) and in the ultrastrong-coupling regime. These models support bound states, in which photonic excitations are confined around the scatterers. These states are essential for understanding some dynamical properties. We illustrate this by studying the spontaneous decay of a two-level atom in the RWA. We have determined some analytical properties of the scattering matrix in Chap. 4, the most important mathematical object in this field. In particular, we have shown that the cluster decomposition principle for the scattering amplitudes, which arises in quantum field theories because those are relativistic, also holds in our case, even though we are dealing with nonrelativistic models. We have generalized the cluster principle to scatterers with memory, finding the structure of the scattering matrix compatible with this principle. We have also considered scattering in linear systems, that is, systems in which the Heisenberg equations of motions are linear in the operators. We have shown that this scattering matrix induces no correlations and neither annihilation nor creation of photons are allowed. We support our mathematical results with some simulations using MPS. We are able to control how nonlinear the scatterers are, finding a suppression of the nonlinear features of the scattering when the scatterers are linear. We have studied several instances of few-photon scattering in Chap. 5 using the methods introduced in Chap. 2. We have fully characterized the one-photon scattering from a two-level atom in the ultrastrong regime, where deterministic inelastic scattering is possible. We have found also deterministic two-photon generation in the one-photon scattering from a cyclic three-level atom. The one- and two-photon scattering from a generalized V atom has been studied, where we can have perfect transmission both for one and two photons; besides, we can switch on and off the generation of photon-photon correlations in the two-photon scattering. We propose an implementation of a two-qubit quantum phase gate. In order to do so, we have considered two-photon scattering with nonmonochromatic wave packets from different instances of point-like scatterers. Unfortunately, even though the process is feasible, the efficiency is too low. Finally, we have studied the effects of interqubit distance in twophoton scattering

Reishi SAS

El trabajo aquí presentado es la materialización de una idea de Diseño, Montaje y Puesta en Marcha de un Cultivo de Hongos Medicinales en el municipio de La Mesa Cundinamarca, como alternativa de desempeño profesional, ante la situación de desempleo actual y la necesidad de impulsar el emprendimiento como una nueva iniciativa en la sociedad colombiana. Esta idea surge de una experiencia anterior de uno de los colaboradores del equipo de trabajo.The work presented is the materialization of an idea of Design, Assembly and launching of Medicinal Mushroom Growing in La Mesa – Cundinamarca, Colombia -, as an alternative to professional performance before the current unemployment in national environment, as well as our desire to promote entrepreneurship as a more active initiative in Colombia. This idea stems from a previous experience of one of the collaborators of our work team.Especialista en Administración Financier

Analizando la motivación en el deporte: un estudio a través de la teoría de la autodeterminación

En este trabajo se trataron de establecer relaciones entre los elementos que definen la Teoría de las Metas de Logro de Nicholls y la Teoría de la Autodeterminación de Deci y Ryan, así como analizar las diferencias existentes en función de una serie de variables demográficas. Para ello se empleó una muestra de 413 deportistas de diversos deportes con edades comprendidas entre los 12 y 16 años, que respondieron el POSQ, PMCSQ-2 y SMS. Los resultados revelan que los deportistas con un alto SDI muestran una mayor orientación a la tarea y perciben en mayor medida un clima tarea que los deportistas con un bajo SDI, que tienen una mayor orientación al ego y una mayor percepción de un clima ego. Además, los chicos muestran una mayor orientación al ego y perciben un clima motivacional más implicante al ego que las chicas, que perciben un clima motivacional más implicante a la tarea y tienen un mayor SDI. También se ha encontrado que los deportistas más jóvenes perciben un mayor clima tarea, y que un mayor tiempo de práctica se relaciona con un mayor SDI. Los deportistas de deportes colectivos tienen una mayor orientación al ego y una mayor percepción de un clima ego, mientras que en los deportes individuales es mayor la orientación a la tarea y el SDI.This paper is an attempt to establish relationships among elements that define the Achievement Goal Theory (Nicholls) and the Self-determination Theory (Deci & Ryan), as well as to analyze existing differences, depending on several demographic variables. A sample of 413 athletes of different sports, ranging in age from 12 to 16, who responded the POSQ, PMCSQ-2 and SMS, was used for it. The results reveal that athletes with high SDI show higher task orientation and perceive higher task-involving climate than athletes with low SDI, who have higher ego orientation and higher ego-involving climate perception. Also, boys show higher ego orientation and perceive higher ego-involving motivational climate than girls, who perceive higher task-involving motivational climate and have higher SDI. It has also been found that youngest athletes perceive higher taskinvolving climate, and that higher practice time is related with higher SDI. Team sport athletes have higher ego orientation and higher ego-involving climate perception, while task orientation and SDI is higher in individual sports