Search results for "Coupling"
showing 10 items of 1862 documents
Emission properties of single InAs/GaAs quantum dot pairs and molecules grown in GaAs nanoholes
2010
Trabajo presentado a la "11th International Conference on Optics of Excitons in Confined Systems" (OECS), celebrada en en Madrid (España) del 7 al 11 de Septiembre de 2009.
Energy-level repulsion by spin-orbit coupling in two-dimensional Rydberg excitons
2018
We study the effects of Rashba spin-orbit coupling on two-dimensional Rydberg exciton systems. Using analytical and numerical arguments we demonstrate that this coupling considerably modifies the wave functions and leads to a level repulsion that results in a deviation from the Poissonian statistics of the adjacent level distance distribution. This signifies the crossover to non-integrability of the system and hints on the possibility of quantum chaos emerging. Such a behavior strongly differs from the classical realization, where spin-orbit coupling produces highly entangled, chaotic electron trajectories in an exciton. We also calculate the oscillator strengths and show that randomization…
Spin transfer torques and spin-dependent transport in a metallic F/AF/N tunneling junction
2018
We study spin-dependent electron transport through a ferromagnetic-antiferromagnetic-normal metal tunneling junction subject to a voltage or temperature bias, in the absence of spin-orbit coupling. We derive microscopic formulas for various types of spin torque acting on the antiferromagnet as well as for charge and spin currents flowing through the junction. The obtained results are applicable in the limit of slow magnetization dynamics. We identify a parameter regime in which an unconventional damping-like torque can become comparable in magnitude to the equivalent of the conventional Slonczewski's torque generalized to antiferromagnets. Moreover, we show that the antiferromagnetic sublat…
Microwave heating as a tool for coupling Marangoni and Hickman instabilities
2007
The aim of this paper is the linear stability analysis of an evaporating interface in order to justify hydrodynamic behaviors observed during evaporation of water and ethanol simultaneously under microwave irradiation and reduced pressure. In relation to the local character of the thermal conversion of electromagnetic energy, and of the thermal dependency of the dielectric loss, it seems possible under microwave heating to induce a specific hydrodynamic compared to those induced by conventional heating.
Isobar width effects in the coupling of nucleon to isobar channels
1986
The investigation of the effects of isobar coupling to two-nucleon channels has been extended to include additional physical features. A new code discretizes the mass distribution of the isobar widths and treats each mass as a separate channel. This allows the treatment of width in the presence of coupling by transition potentials, in addition to the previously permitted boundary coupling. It also produces the S-italic-matrix components required to describe the many-body final-state distributions. When indicated by the one-pion-exchange coupling strength new isobar channels are included. The new results for nucleon-nucleon scattering fit the data better, starting from more realistic models.…
Parametrization of scatterers in the Landauer-Büttiker transport theory.
1993
Electronic dc transport along a finite chain of scatterers that allow for elastic as well as inelastic processes is described within the Landauer-Buttiker approach. The transport channels in the chain are locally coupled via (current-conserving) side channels to electron reservoirs or heat baths that provide the phase randomization. Different choices for the parameters describing the inelastic coupling as well as the elastic (transmission and reflection) coefficients are compared. The scattering matrix of the chain is calculated with a recursive method. We show that the most general individual scatterer can be characterized by five parameters only, and that it can be represented by a subset…
Single-Ion Heat Engine at Maximum Power
2012
We propose an experimental scheme to realize a nanoheat engine with a single ion. An Otto cycle may be implemented by confining the ion in a linear Paul trap with tapered geometry and coupling it to engineered laser reservoirs. The quantum efficiency at maximum power is analytically determined in various regimes. Moreover, Monte Carlo simulations of the engine are performed that demonstrate its feasibility and its ability to operate at a maximum efficiency of 30% under realistic conditions.
Fluorescence relaxation in the near-field of a mesoscopic metallic particle : distance dependence and role of plasmon modes
2008
International audience; We analytically and numerically analyze the fluorescence decay rate of a quantum emitter placed in the vicinity of a spherical metallic particle of mesoscopic size (i.e with dimensions comparable to the emission wavelength). We discuss the efficiency of the radiative decay rate and non–radiative coupling to the particle as well as their distance dependence. The electromagnetic coupling mechanisms between the emitter and the particle are investigated by analyzing the role of the plasmon modes and their nature (dipole, multipole or interface mode). We demonstrate that near-field coupling can be expressed in a simple form verifying the optical theorem for each particle …
What can be learned from the rotational motion of single molecules in a polymer melt near the glass transition?
2007
We develop a framework for the interpretation of single-molecule (SM) spectroscopy experiments of probe dynamics in a complex glass-forming system. Specifically, from molecular dynamics simulations of a single probe molecule in a coarse-grained model of a polymer melt, we show the emergence of sudden large angular reorientations (SLARs) of the SM as the mode coupling critical temperature is closely approached. The large angular jumps are intimately related to meta-basin transitions in the potential energy landscape of the investigated system and cause the appearance of stretched exponential relaxations of various rotational observables, reported in the SM literature as dynamic heterogeneity…
Search for supersymmetric particles with R-parity violation in Z decays
1995
Searches for supersymmetric particles produced in e(+)e(-) interactions at the Z peak have been performed under the assumptions that R-parity is not conserved, that the dominant R-parity violating coupling involves only leptonic fields, and that the lifetime of the lightest supersymmetric particle can be neglected. In a data sample collected by the ALEPH detector at LEP up to 1993, and corresponding to almost two million hadronic Z decays, no signal was observed. As a result, supersymmetric particle masses and couplings are at least as well constrained as under the usual assumption of R-parity conservation.