Phase-space analysis of bosonic spontaneous emission

We present phase-space techniques for the modelling of spontaneous emission in two-level bosonic atoms. The positive-P representation is shown to give a full and complete description and can be further developed to give exact treatments of the interaction of degenerate bosons with the electromagnetic field in a given experimental situation. The Wigner representation, even when truncated at second order, is shown to need a doubling of the phase-space to allow for a positive-definite diffusion matrix in the appropriate Fokker-Planck equation and still fails to agree with the full quantum results of the positive-P representation. We show that quantum statistics and correlations between the ground and excited states affect the dynamics of the emission process, so that it is in general non-exponential.Comment: 16 pages, 6 figure

Quantum theory of a polarization phase-gate in an atomic tripod configuration

We present the quantum theory of a polarization phase-gate that can be realized in a sample of ultracold rubidium atoms driven into a tripod configuration. The main advantages of this scheme are in its relative simplicity and inherent symmetry. It is shown that the conditional phase shifts of order $\pi$ can be attained.Comment: X International Conference on Quantum Optics, Minsk, Belaru

Prospects for photon blockade in four level systems in the N configuration with more than one atom

We show that for appropriate choices of parameters it is possible to achieve photon blockade in idealised one, two and three atom systems. We also include realistic parameter ranges for rubidium as the atomic species. Our results circumvent the doubts cast by recent discussion in the literature (Grangier et al Phys. Rev Lett. 81, 2833 (1998), Imamoglu et al Phys. Rev. Lett. 81, 2836 (1998)) on the possibility of photon blockade in multi-atom systems.Comment: 8 page, revtex, 7 figures, gif. Submitted to Journal of Optics B: Quantum and Semiclassical Optic

Prefactibilidad en la creación de un hostal en la comuna de Providencia

Tesis (Ingeniero Industrial)En la presente tesis se realizará un estudio de prefactibilidad para la Creación de un Hostal en la Comuna de Providencia, en donde se desea plantear el desarrollo de un nuevo proyecto que promueva el turismo en la capital. Se incurrirá en diferentes estudios, comenzando por un estudio de mercado en donde se conocerá el comportamiento de la oferta y demanda de este tipo de negocio y los servicios que este entregará. Además se efectuara un estudio técnico que visualizará la viabilidad operacional y técnica, a su vez determinar la disponibilidad tanto de recursos físicos como humanos para el desarrollo de la actividad. Finalmente la realización de un estudio financiero que permita determinar la rentabilidad del proyecto. El objetivo principal del trabajo es demostrar la factibilidad económica y atractivo de un hostal con servicio de tour a la medida en la comuna de Providencia. Nuestro mercado objetivo se compone de Turistas Nacionales e Internacionales, hombres y mujeres pertenecientes a la segmentación socio-económica ABC1-C2, que tienen entre 10 y 65 años. Del análisis Porter que se realizó a la industria descubrimos que el atractivo de la industria y del proyecto es medio-alto. Luego de realizar el FODA las fortalezas observadas pueden contrarrestar las debilidades que, sin duda pueden revertirse en el futuro. Además, las oportunidades son considerables y se visualiza la prosperidad de este rubro, por ello, las amenazas se verían disminuidas. En cuanto a las operaciones explicaremos el organigrama, la infraestructura y el diagrama de flujo del servicio. En el análisis financiero realizado vemos que el proyecto presenta un VAN mayor a cero, con un valor de UF4.895 al año 10, es decir, el proyecto recupera lo invertido y retorna la tasa exigida. Por otro lado, la TIR que corresponde a la rentabilidad del proyecto es igual a 70.28% y el PRI es en 2 años

Clinical analysis of etiology, risk factors and outcome in patients with acute kidney injury.

Acute kidney injury is characterized by a rapid loss of renal excretory function with the increase of nitrogen compounds in the blood and with different outcome. Objective: Since descriptions of the risk factors and sequelae of acute kidney injury (AKI) remain relatively limited, the objective of this study was to determine etiology and clinical characteristics of AKI, as well as risk factors for adverse outcome of renal function and death in AKI patients. Methods: We retrospectively studied a cohort of 84 adult AKI patients admitted to Nephrology Clinic in University Clinical Centre Sarajevo during period 2012-2014. Demographic, laboratory and clinical parameters were retrieved. The in-hospital and 6 months mortality were recorded. Renal function outcome was defined 3 months following discharge. Results: Majority of patients were older (median age 73.5 years) with great severity of AKI (Stage III in 78.5% of cases) and high burden of comorbidities (mean Charlson comorbidity index, CCI score 6.4±3.05). The most common causes of AKI were acute interstitial nephritis (16.7%), heart failure (15.5%), gastroenterocolitis (13.1%), and sepsis (12%). Renal function recovery was recorded in 48.8% of patients, with prevalence of 10.7% of intrahospital mortality and 37.3% of 6 months mortality. Risk factors for poor outcome of renal function and mortality in AKI patients were increasing age and higher CCI score, while protective factor was higher diuresis. Sepsis proved to be risk factor for deat

A proposal for an optical implementation of a universal quantum phase gate

Large optical nonlinearities occurring in a coherently prepared atomic system are shown to produce phase shifts of order pi. Such an effect may be observed in ultracold rubidium atoms where it could be feasibly exploited toward the realization of a polarization phase gate