Entanglement transfer via two arrays of coupled resonator waveguides

We propose a scheme for transferring entanglement through two independent arrays of coupled resonator waveguides, where a three-level atom is embedded in each resonator. We investigate the entanglement dynamics of the transferred state. The influence of initial states and applied lasers on the entanglement sudden death phenomenon is also discussed. Furthermore, we study the dynamics of pairwise quantum correlations measured by the quantum discord.     

Entanglement transfer via two arrays of coupled resonator waveguides

We propose a scheme for transferring entanglement through two independent arrays of coupled resonator waveguides,where a three-level atom is embedded in each resonator.We investigate the entanglement dynamics of the transferred state.The influence of initial states and applied lasers on the entanglement sudden death phenomenon is also discussed.Furthermore,we study the dynamics of pairwise quantum correlations measured by the quantum discord.     

Spontaneous decay rates in active waveguides

We present a new method of measuring the guided, radiated, and total decay rates in uniform waveguides. It is also shown theoretically that large modifications of the total decay rate can be achieved in realistic erbium-doped fiber amplifiers and erbium-doped waveguide amplifiers with effective mode area radii smaller than approximately 1 microm.     

Lateral and longitudinal coupled waveguides in semiconductor lasers

A semiconductor laser including two laterally coupled waveguides, in which one of the waveguides includes a partially reflecting surface (an internal mirror) between its facets, is analyzed. The internal mirror inserts longitudinal coupling into the system. The spectrum of the Fabry-Perot modes exhibits modulation in the gain required for lasing threshold, with a periodicity that depends on the longitudinal position of the internal mirror. The combined coupled-cavity effect may explain the observed gain spectrum in GaN lasers.     

Polariton propagation in coupled quantum wire waveguides

The propagation of the excitonic polariton along the directional coupler consisting of adjacent parallel GaAs quantum-wire waveguides is simulated by using a finite element method. It is found that the coupling length is as short as 2.5-4 μm, which is three orders of magnitude shorter than the conventional optical directional coupler made of bulk GaAs. Such short coupling length will make it possible to fabricate extremely small optoelectronic devices such as directional-coupler-type switches.     

Accounting for delay of energy transfer between coupled rooms in statistical-acoustics models of reverberant-energy decay

A statistical-acoustics model for energy decay in systems of two or more coupled rooms is introduced, which accounts for the distribution of delay in the transfer of energy between subrooms that results from the finite speed of sound. The method extends previous models based on systems of coupled ordinary differential equations by using functional differential equations to explicitly model dependence on prior values of energy in adjacent subrooms. Predictions of the model are illustrated for a two-room coupled system and compared with the predictions of a benchmark computational geometrical-acoustics model.     

Solitons in a system of coupled graphene waveguides

Propagation of extremely-short optical pulses that can be considered as discrete solitons in a system of graphene waveguides has been studied. The effective equation having the form of an analog of the classical sin-Gordon equation has been derived. The effects observed with varying the initial pulse width have been investigated     

Spatial optical simultons in nonlinearly coupled planar waveguides

With second-harmonic generation in surface and buried planar waveguides achieved by direct and reverse proton exchange in lithium niobate, we demonstrate a novel kind of quadratic spatial simulton: The transverse-electric fundamental input and the transverse-magnetic second-harmonic waves nonlinearly couple two superimposed planar waveguides, permitting transverse localization of light at room temperature and at excitations as low as 340 nJ in 20-ps pulses.     

Anomalous Bloch oscillations in arrays of coupled waveguides

Anomalous Bloch oscillations in arrays of coupled waveguides have been investigated using two different approaches: multiple scattering formalism and coupled-mode model. Both approaches are shown to yield identical results. Formulas for the parameters of the coupled-mode model are derived. An analytical expression for the optical beam path is obtained, and the condition for the existence of anomalous Bloch oscillations is found.     

Superlattices with coupled channels and transfer matrices

We study analytically threshold and resonance effects in superlattices using the well-known transfer matrix technique. For this analysis we take advantage of a new parametrization of the scattering amplitudes. In particular, threshold effects, analogous to the so-called “Wigner cusps” of nuclear reactions, follow when a channel is opened for non-zero coupling. Sharp resonances of Lorenzian shape are also found only in the presence of coupling. It could be very interesting to look for experimental evidences of these effects. We expect that this approach allows to study systems with spin and under external magnetic fields.     

Evaluation of decay times in coupled spaces: Bayesian decay model selection

This paper applies Bayesian probability theory to determination of the decay times in coupled spaces. A previous paper [N. Xiang and P. M. Goggans, J. Acoust. Soc. Am. 110, 1415-1424 (2001)] discussed determination of the decay times in coupled spaces from Schroeder's decay functions using Bayesian parameter estimation. To this end, the previous paper described the extension of an existing decay model [N. Xiang, I. Acoust. Soc. Am. 98, 2112-2121 (1995)] to incorporate one or more decay modes for use with Bayesian inference. Bayesian decay time estimation will obtain reasonable results only when it employs an appropriate decay model with the correct number of decay modes. However, in architectural acoustics practice, the number of decay modes may not be known when evaluating Schroeder's decay functions. The present paper continues the endeavor of the previous paper to apply Bayesian probability inference for comparison and selection of an appropriate decay model based upon measured data. Following a summary of Bayesian model comparison and selection, it discusses selection of a decay model in terms of experimentally measured Schroeder's decay functions. The present paper, along with the Bayesian decay time estimation described previously, suggests that Bayesian probability inference presents a suitable approach to the evaluation of decay times in coupled spaces.     

Step-like structure and assisted tunneling in two coupled modulated waveguides

The propagation of an initially-localized optical beam along two coupled modulated waveguides is investigated. A universal step-like structure emerges in the propagation process once |d|\delta v/v₀|v_0| ~ 1 and T = 2 π/m v₀m v_0, both for the linear and nonlinear optical waveguides. The reason is that the coupling between the two waveguides can be completely suppressed at z = m T or (2 m+1)T/2. When the nonlinearity is strong, assisted tunneling can be found for the initially-localized optical beam by slightly increasing the strength of the modulation.     

Dynamics of coupled waves in optical waveguides with longitudinally distributed dispersion and nonlinearity parameters

The dynamics of a two-wave pulse in an optical waveguide with longitudinally distributed dispersion and nonlinearity parameters subject to linear and cross-modulation coupling of the waves is studied. The duration of the traveling pulse and the rate of its frequency modulation as functions of the longitudinal coordinates are derived for different nonlinearity and group velocity dispersion profiles.     

Characterizing turbulence in globally coupled maps with stochastic finite automata

We describe a method to discriminate between ordered and turbulent behavior in a general class of collective systems known as Globally Coupled Maps (GCM). Our method is able to discover an unknown small ordered region inside the turbulent phase of GCM parameter space. The computational nature of the method is the main novelty of our approach; it is another example of how measures based on computational notions of structure may provide new information in the study of dynamical systems.