Radio-frequency dressed atoms beyond the linear Zeeman effect

We evaluate the impact that nonlinear Zeeman shifts have on resonant radio-frequency (RF) dressed traps in an atom-chip configuration. The degeneracy of the resonance between Zeeman levels is lifted at large intensities of a static field, modifying the spatial dependence of the atomic adiabatic potential. In this context, we find effects that are important for the next generation of atom chips with tight trapping: in particular, that the vibrational frequency of the atom trap is sensitive to the RF frequency and, depending on the sign of the Landé factor, can produce significantly weaker, or tighter trapping when compared to the linear regime of the Zeeman effect. We take 87 Rb as an example and find that it is possible for the trapping frequency on F = 1 to exceed that of the F = 2 hyperfine manifold

Atom chips with two-dimensional electron gases: theory of near surface trapping and ultracold-atom microscopy of quantum electronic systems

We show that current in a two-dimensional electron gas (2DEG) can trap ultracold atoms $<1 \mu$m away with orders of magnitude less spatial noise than a metal trapping wire. This enables the creation of hybrid systems, which integrate ultracold atoms with quantum electronic devices to give extreme sensitivity and control: for example, activating a single quantized conductance channel in the 2DEG can split a Bose-Einstein condensate (BEC) for atom interferometry. In turn, the BEC offers unique structural and functional imaging of quantum devices and transport in heterostructures and graphene.Comment: 5 pages, 4 figures, minor change

Addressed qubit manipulation in radio-frequency dressed lattices

Precise control over qubits encoded as internal states of ultracold atoms in arrays of potential wells is a key element for atomtronics applications in quantum information, quantum simulation and atomic microscopy. Here we theoretically study atoms trapped in an array of radio-frequency dressed potential wells and propose a scheme for engineering fast and high-fidelity single-qubit gates with low error due to cross-talk. In this proposal, atom trapping and qubit manipulation relies exclusively on long-wave radiation making it suitable for atom-chip technology. We demonstrate that selective qubit addressing with resonant microwaves can be programmed by controlling static and radio-frequency currents in microfabricated conductors. These results should enable studies of neutral-atom quantum computing architectures, powered by low-frequency electromagnetic fields with the benefit of simple schemes for controlling individual qubits in large ensembles

En busca del proyecto ideal. Una orientación para la exploración de proyectos y su formulación

Este artículo le brindará la posibilidad de visualizar algunas notas del autor, la proposición de un par de metodologías para la gestión de proyectos, la sugerencia de algunos proyectos y la mención de ciertas guías que le permitirán ubicar de forma estratégica, geográfica, histórica y financiera un proyecto. Dentro de los elementos a ser considerados se encuentra: usar como guía de ubicación el Plan de Desarrollo Territorial de su municipio, departamento o país. Reconocer o usar el análisis de las cadenas productivas de diferentes productos, que ofrece el Departamento Nacional de Planeación. Usar el documento del Consejo Nacional de Política Económica y Social (CONPES) 3527 - Departamento Nacional de Planeación. Visualizar las oportunidades que tienen los Tratados de Libre Comercio (TLC) para Colombia. Las metodologías propuestas para buscar, formular y ejecutar proyectos, son Project Management Institute (PMI®) y Marco Lógico. Se recomienda tener precaución con el análisis financiero, las regulaciones y la gestión de riesgos. Dentro de los temas para proyectos propuestos se encuentran: la Responsabilidad Social Empresaria (RSE); el “Pensamiento Estratégico” para hacer un análisis estructural del sector estratégico; la teoría de restricciones (TOC - “Theory of Constraints”); la gestión de conocimiento; gestión de la información; ver la necesidad del desarrollo personal; el liderazgo; el Balanced Scorecard; la seguridad informática, Business Continuity Plan (BCP), contingencia y sistemas de gestión integrados

El demonio entre las sabanas : historias ejemplares para señoritas santafereñas

El ejercicio del control persiste a través de las épocas, y los comportamientos sociales del colectivo continúan adecuándose a éste como una forma de pertenecer a un estatus quo que, a la mejor manera de la caza de brujas, persigue lo anormal y lo destruye. Los conceptos de naturalidad y normalidad han sido utilizados para excluir cualquier comportamiento disidente del orden establecido de los roles de género y la identidad del nosotros respecto al otro. En el presente documento, se busca la exploración de las categorías de normal y anormal. Se pretende también hacer un análisis de las relaciones entre el individuo y el colectivo y cómo éstas moldean la percepción de sí mismo y las conductas conformistas, transgresoras o autodestructivas que adopta en su relación con el otro y los ideales de conducta. Se pretende, entonces, no proponer una solución sino mostrar una problemática que nos afecta como seres humanos y que desmonta el mito del progreso y la liberación sexual. Así mismo, el mostrar esta alteridad histórica pretende ayudar a construir una versión que sirve como alternativa a la oficial.LGBTThe control excercise surives through the ages, adapting social behaviours as a way to be part of a status quo that intends to pursue and destroy, as the witch hunts, everything classified as “abnormal”. The concepts of “nomality” and “naturalness” has been used to exclude any behaviour that dissents from and stablished order, in terms of gender roles and identity of the collective group to the individual. In the present document, an exploration of the categories of “normal” and “abnormal” is intended. It is pretended as well to analyze the relationships between an individual and a collective group, and how those mold the perceptions of oneself and the comformist, transgressive and self destructive behaviours that can be adopted with the others and the ideals of self. It is purported, then, not to propose a solution but to present a problem that affects us as human beings, and to dismantle the myth of progress and sexual liberation. Moreover, to present this historical artlessness could help to construct a new, alternative to the oficial version.Maestro (a) en Artes VisualesPregrad

Non-adiabatic pumping in an oscillating-piston model

We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase-space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.Comment: 6 pages, 4 figures, improved versio

Atom chips with free-standing two-dimensional electron gases: advantages and challenges

In this work, we consider the advantages and challenges of using free-standing two-dimensional electron gases (2DEG) as active components in atom chips for manipulating ultracold ensembles of alkali atoms. We calculate trapping parameters achievable with typical high-mobility 2DEGs in an atom chip configuration and identify advantages of this system for trapping atoms at submicron distances from the atom chip. We show how the sensitivity of atomic gases to magnetic field inhomogeneity can be exploited for controlling the atoms with quantum electronic devices and, conversely, using the atoms to probe the structural and transport properties of semiconductor devices

En busca del proyecto ideal. Una orientación para la exploración de proyectos y su formulación

Este artículo le brindará la posibilidad de visualizar algunas notas del autor, la proposición de un par de metodologías para la gestión de proyectos, la sugerencia de algunos proyectos y la mención de ciertas guías que le permitirán ubicar de forma estratégica, geográfica, histórica y financiera un proyecto. Dentro de los elementos a ser considerados se encuentra: usar como guía de ubicación el Plan de Desarrollo Territorial de su municipio, departamento o país. Reconocer o usar el análisis de las cadenas productivas de diferentes productos, que ofrece el Departamento Nacional de Planeación. Usar el documento del Consejo Nacional de Política Económica y Social (CONPES) 3527 - Departamento Nacional de Planeación. Visualizar las oportunidades que tienen los Tratados de Libre Comercio (TLC) para Colombia. Las metodologías propuestas para buscar, formular y ejecutar proyectos, son Project Management Institute (PMI®) y Marco Lógico. Se recomienda tener precaución con el análisis financiero, las regulaciones y la gestión de riesgos. Dentro de los temas para proyectos propuestos se encuentran: la Responsabilidad Social Empresaria (RSE); el “Pensamiento Estratégico” para hacer un análisis estructural del sector estratégico; la teoría de restricciones (TOC - “Theory of Constraints”); la gestión de conocimiento; gestión de la información; ver la necesidad del desarrollo personal; el liderazgo; el Balanced Scorecard; la seguridad informática, Business Continuity Plan (BCP), contingencia y sistemas de gestión integrados

Quantum properties of Bose-Einstein condensates coupled to semiconductor heterojunctions

In this thesis, we present a theoretical study of the effects that a current-carrying Two-Dimensional Electron Gas (2DEG) produce on a neighbouring magnetically trapped Bose-Einstein Condensate of alkali atoms (BEC). We suggest that technology used for magnetic micro-controlling of cold gases could be improved by replacing or combining the metallic wires used in such structures with 2DEG-based conductors or quantum electronic devices. All calculations presented in this thesis consider parameters attainable with present technology, suggesting that experimental realization of the scenarios proposed here is already feasible. In Chapter one we present the general context in which this thesis is developed. It includes a definition of the Bose-Einstein condensate state, a description of the principles of magnetic trapping and a brief review of the developments in the area of micromanipulation of atomic BECs. Chapter two is devoted to describe the characteristics of the heterojunction considered in the thesis, and a simple model used to evaluate the electron flow in the 2DEG it contains. Chapter three shows in detail the properties of magnetic trapping configurations considered afterwards. We study two simple applications that can be developed by bringing a BEC near to a current carrying 2DEG. Firstly, in Chapter four, we demonstrate the feasibility of creating magnetic trapping potentials using a current-carrying 2DEG and an external magnetic field. We identify the advantages of such a 2DEG-based trap over traditional metal-based traps and the conditions needed for operability. Recently developed techniques of magnetic field microscopy with BECs motivate our second considered application, namely, using a Bose-Einstein Condensate to probe the electron transport in 2DEGs and structural characteristics of the heterojunction. In Chapter five, we demonstrate how the quantization of conductance occurring in Quantum Point Contacts (QPC) fabricated from the heterojunction in the 2DEG, can be detected through a localized depletion of the BEC caused by a small inhomogeneity of the magnetic field that originates from a current through the QPC. In addition, we show that the electron density fluctuations in the 2DEG can be measured by detecting the corresponding inhomogeneous magnetic field produced when current flows, via modulation of the BEC’s density. We establish the conditions under which a sensitive response of the BEC to the magnetic field is possible. We also derive a general relation between the modulation of the magnetic field affecting the BEC and the distribution of ionized donors in the heterojunction. Creating semiconductor-cold-atom hybrid systems, where electrons in the semiconductor and atoms in the BEC are coupled to each other, requires a full understanding of the properties of both systems. Since typical micro-traps have an elongated geometry, in Chapter six we present a study of phase correlations of BECs in such geometries. To do this, we use a recently proposed effective one-dimensional equation that takes into account the 3D character of the BEC. Finally, in Chapter seven, we conclude and identify directions for future work emerging from this thesis