Definition of the stimulated emission threshold in high-β\beta nanoscale lasers through phase-space reconstruction

Nanoscale lasers sustain few optical modes so that the fraction of spontaneous emission $\beta$ funnelled into the useful (lasing) mode is high (of the order of few 10$^{-1}$) and the threshold, which traditionally corresponds to an abrupt kink in the light in- light out curve, becomes ill-defined. We propose an alternative definition of the threshold, based on the dynamical response of the laser, which is valid even for $\beta=1$ lasers. The laser dynamics is analyzed through a reconstruction of its phase-space trajectory for pulsed excitation. Crossing the threshold brings about a change in the shape of the trajectory and in the area contained in it. An unambiguous definition of the threshold in terms of this change is shown theoretically and illustrated experimentally in a photonic crystal laser

Bioetanol dari Limbah Kulit Singkong (Manihot Esculenta Crantz) melalui Proses Fermentasi

Carbohydrates can be obtained from tubers such as cassava. Cassava is a plant from family euphorbiaceae and typical tropical plants. Cassava peel is a major waste that contains carbohydrates. The peel of cassava can be used as an energy source, namely ethanol.The purpose of this study is to determine the contents of ethanol through the fermentation process of cassava peel where obtainable from Malino village, Batu Daka West, Tojo Una-Una. The parameters in this study was content of ethanol that was obtained by fermentation using saccaromyces cerevisiae yeast. The fermentation process was conducted by varying day of fermentation, 4, 6, 8, and 10 days. The results showed the fermentation of ethanol with time variation respectively is 4.50, 5.20, 6.00 and 4.00%. In conclusion, it can be said that the highest ethanol content is 6.00% with the fermentation time of 8 days

Pemanfaatan Biomassa Serbuk Gergaji sebagai Penyerap Logam Timbal

Lead (Pb) is one kind of heavy metal that has high level of toxicity. One way to reduce the level of Pb is by adsorption using cellulose and lignin of sawdust. The aim of this study is to determine the optimum pH, the optimum weight and to determine the adsorption capacity of sawdust when it absorbs Pb in solution of Pb(NO3)2. The adsorption process is carried out by using the various pH of 3, 4, 5, 6, 7, and 8 with a weight of 100 mg, and then the various weight of 100, 200, 300, 400, and 500 mg with the pH optimum. The analysis of Pb content in the solution was conducted by Spectro-direct. The analysis result shows the determination of pH occured at pH 7, Pb absorbed is 14.89 mg/g, and the percentage of Pb absorbed was 96.97%. For the determination of 400 mg of the adsorbent weight of Pb absorbed was 3,83 mg/g, the adsorption percentage of Pb was 99.98%, and the optimum adsorption for optimum weight was 0.15 mg Pb/mg sawdust

Alternative approach to electromagnetic field quantization in nonlinear and inhomogeneous media

A simple approach is proposed for the quantization of the electromagnetic field in nonlinear and inhomogeneous media. Given the dielectric function and nonlinear susceptibilities, the Hamiltonian of the electromagnetic field is determined completely by this quantization method. From Heisenberg's equations we derive Maxwell's equations for the field operators. When the nonlinearity goes to zero, this quantization method returns to the generalized canonical quantization procedure for linear inhomogeneous media [Phys. Rev. A, 43, 467, 1991]. The explicit Hamiltonians for the second-order and third-order nonlinear quasi-steady-state processes are obtained based on this quantization procedure.Comment: Corrections in references and introductio

Survival of quantum effects for observables after decoherence

When a quantum nonlinear system is linearly coupled to an infinite bath of harmonic oscillators, quantum coherence of the system is lost on a decoherence time-scale $\tau_D$. Nevertheless, quantum effects for observables may still survive environment-induced decoherence, and be observed for times much larger than the decoherence time-scale. In particular, we show that the Ehrenfest time, which characterizes a departure of quantum dynamics for observables from the corresponding classical dynamics, can be observed for a quasi-classical nonlinear oscillator for times $\tau \gg\tau_D$. We discuss this observation in relation to recent experiments on quantum nonlinear systems in the quasi-classical region of parameters.Comment: submitted to PR

Mode structure and ray dynamics of a parabolic dome microcavity

We consider the wave and ray dynamics of the electromagnetic field in a parabolic dome microcavity. The structure of the fundamental s-wave involves a main lobe in which the electromagnetic field is confined around the focal point in an effective volume of the order of a cubic wavelength, while the modes with finite angular momentum have a structure that avoids the focal area and have correspondingly larger effective volume. The ray dynamics indicates that the fundamental s-wave is robust with respect to small geometrical deformations of the cavity, while the higher order modes are associated with ray chaos and short-lived. We discuss the incidence of these results on the modification of the spontaneous emission dynamics of an emitter placed in such a parabolic dome microcavity.Comment: 50 pages, 17 figure

Cumulant expansion for studying damped quantum solitons

The quantum statistics of damped optical solitons is studied using cumulant-expansion techniques. The effect of absorption is described in terms of ordinary Markovian relaxation theory, by coupling the optical field to a continuum of reservoir modes. After introduction of local bosonic field operators and spatial discretization pseudo-Fokker-Planck equations for multidimensional s-parameterized phase-space functions are derived. These partial differential equations are equivalent to an infinite set of ordinary differential equations for the cumulants of the phase-space functions. Introducing an appropriate truncation condition, the resulting finite set of cumulant evolution equations can be solved numerically. Solutions are presented in Gaussian approximation and the quantum noise is calculated, with special emphasis on squeezing and the recently measured spectral photon-number correlations [Spaelter et al., Phys. Rev. Lett. 81, 786 (1998)].Comment: 17 pages, 13 figures, revtex, psfig, multicols, published in Phys.Rev.

The transferencial relation beyond the interpretation : reflections from the theory of Winnicott.

Este artigo reflete sobre a importância de pensar a relação transferencial na clínica psicanalítica para além da interpretação. Para isso, utiliza-se a concepção de Winnicott como referencial teórico, sendo ressaltadas a noção de holding, a regressão à dependência e a questão do uso de objetos e sua influência sobre a técnica da interpretação. Winnicott revela que na clínica com alguns pacientes, em especial os autistas e psicóticos, o objetivo da análise, antes de fornecer interpretações, é proporcionar um ambiente suficientemente bom a partir do qual o sujeito pode retomar o processo de constituição de si mesmo e da externalidade do mundo.This article reflects about the importance of thinking the transferencial relation in the psychoanalytic clinic beyond the interpretation. For this, the Winnicott’s concept is used as theoretical reference, highlighting the concept of holding, regression to dependence and the question of the use of objects and its influence on the technique of interpretation. Winnicott shows that in the clinic, with some patients, particularly autistic and psychotic, before providing interpretation, the objective of the analysis is to provide a good environment from which the subject can retake the constitution process of himself/herself and of the externality of the world