Quantum dissipation of planar harmonic systems: Maxwell-Chern-Simons theory

The conventional Brownian motion in harmonic systems has provided a deep understanding of a great diversity of dissipative phenomena. We address a rather fundamental microscopic description for the (linear) dissipative dynamics of two-dimensional harmonic oscillators that contains the conventional Brownian motion as a particular instance. This description is derived from first principles in the framework of the so-called Maxwell-Chern-Simons electrodynamics, or also known, Abelian topological massive gauge theory. Disregarding backreaction effects and endowing the system Hamiltonian with a suitable renormalized potential interaction, the conceived description is equivalent to a minimal-coupling theory with a gauge field giving rise to a fluctuating force that mimics the Lorentz force induced by a particle-attached magnetic flux. We show that the underlying symmetry structure of the theory (i.e. time-reverse asymmetry and parity violation) yields an interacting vortex-like Brownian dynamics for the system particles. An explicit comparison to the conventional Brownian motion in the quantum Markovian limit reveals that the proposed description represents a second-order correction to the well-known damped harmonic oscillator, which manifests that there may be dissipative phenomena intrinsic to the dimensionality of the interesting system.Comment: 20+11 pages, 3 figures. Comments are welcome. Discussion in Sec. III and IV improved. Several typos and a misleading remark corrected, and figure replaced. Close to the published versio

Statistical physics of flux-carrying Brownian particles

Chern-Simons gauge field theory has provided a natural framework to gain deep insight about many novel phenomena in two-dimensional condensed matter. We investigate the nonequilibrium thermodynamics properties of a (two-dimensional) dissipative harmonic particle when the Abelian topological gauge action and the (linear) Brownian motion dynamics are treated on an equal footing. We find out that the particle exhibits remarkable magneticlike features in the quantum domain that are beyond the celebrated Landau diamagnetism: this could be viewed as the non-relativistic Brownian counterpart of the composite excitation of a charge and magneticlike flux. Interestingly, it is shown that the properties of such flux-carrying Brownian particle are in good agreement with the classical statistical mechanics at sufficient high temperatures, as well as are widely consistent with the Third Law of thermodynamics in the studied dissipative scenarios. Our findings also suggest that its ground state may be far from trivial, i.e. it fakes a seemingly degenerate state.Comment: 18+6 pages. 8 figures. Comments are welcome. Improved introduction and conclusion. Minor changes in the abstract and main par

Gaussian entanglement induced by an extended thermal environment

We study stationary entanglement among three harmonic oscillators which are dipole coupled to a one-dimensional or a three-dimensional bosonic environment. The analysis of the open-system dynamics is performed with generalized quantum Langevin equations which we solve exactly in Fourier representation. The focus lies on Gaussian bipartite and tripartite entanglement induced by the highly non-Markovian interaction mediated by the environment. This environment-induced interaction represents an effective many-parties interaction with a spatial long-range feature: a main finding is that the presence of a passive oscillator is detrimental for the stationary two-mode entanglement. Furthermore, our results strongly indicate that the environment-induced entanglement mechanism corresponds to uncontrolled feedback which is predominantly coherent at low temperatures and for moderate oscillator-environment coupling as compared to the oscillator frequency.Comment: 15 page, 6 figure

Gaussian tripartite entanglement out of equilibrium

The stationary multipartite entanglement between three interacting harmonic oscillators subjected to decoherence is analyzed in the largely unexplored non-equilibrium strong dissipation regime. We compute the exact asymptotic Gaussian state of the system and elucidate its separability properties, qualitatively assessing the regions of the space of parameters in which fully inseparable states are generated. Interestingly, the sharing structure of bipartite entanglement is seen to degrade as dissipation increases even for very low temperatures, at which the system approaches its ground state. We also find that establishing stationary energy currents across the harmonic chain does not correspond with the build-up of biseparable steady states, which relates instead just to the relative intensity of thermal fluctuations.Comment: 9 pages, 5 figures; accepte

Wigner instability analysis of the damped Hirota equation

We address the modulation instability of the Hirota equation in the presence of stochastic spatial incoherence and linear time-dependent amplification/attenuation processes via the Wigner function approach. We show that the modulation instability remains baseband type, though the damping mechanisms substantially reduce the unstable spectrum independent of the higher-order contributions (e.g. the higher-order nonlinear interaction and the third-order dispersion). Additionally, we find out that the unstable structure due to the Kerr interaction exhibits a significant resilience to the third-order-dispersion stabilizing effects in comparison with the higher-order nonlinearity, as well as a moderate Lorentzian spectrum damping may assist the rising of instability. Finally, we also discuss the relevance of our results in the context of current experiments exploring extreme wave events driven by the modulation instability (e.g. the generation of the so-called rogue waves).Comment: 7+4 pages. 3 figures. Comments are welcome. To appear in Physica

Hierarchies of multipartite entanglement for continuous-variable states

We derive a hierarchy of separability criteria for multi-mode continuous variable systems. They permit to study in a unified way the k-partite entanglement of broad classes of Gaussian and non- Gaussian states. With specific examples we demonstrate the strength of the criteria, and, we discuss their assessment based on data obtained from Gaussian measurements.Comment: minor changes, typos corrected, Ref.[28] adde

Rubinstein Taybi Syndrome. A Case Report

Os autores descrevem um caso de Síndrome de Rubinstein-Taybi em que as características faciais e os polegares alargados permitiram o diagnóstico na primeira semana de vida. Salientam na evolução as infecções respiratórias de repetição, o atraso psicomotor e estaturo ponderal. Discutem as prováveis formas de transmissão deste síndrome

Imunoglobulina Intravenosa na Isoimunização Rh do Recém-Nascido

Estudaram-se retrospectivamente 38 processos de Recém-Nascidos (RN) com isoimunização Rh, 25 dos quais foram tratados com imunoglobulina intravenosa (IGIV) — 500 mg/Kg. Esta terapêutica iniciada no ano 1995 teve como objectivo diminuir a hemólise e consequentemente evitar a exsanguíneo- -transfusão (ET) que seria sempre efectuada desde que se verificassem os critérios classicamente aceites para a evolução e níveis séricos de bilirrubina. Os resultados obtidos mostraram que apenas 28% dos 25 RN que fizeram IGIV necessitaram de ET contrastando com 92% dos 13 casos diagnosticados nos 2 anos imediatamente anteriores ao início desta terapêutica. Parece assim ter sido eficaz na contenção da hemólise mesmo quando a apresentação inicial da doença evidenciou uma anemia que necessitou de ser corrigida. A transfusão de concentrado eritrocitário foi efectuada logo no 1.° dia a 13 dos 25 RN, 68% de todos os casos transfundidos em toda a evolução da doença. Admitimos que esta terapêutica seja uma alternativa válida com menor morbilidade. No nosso estudo não verificámos qualquer efeito secundário