Topic
Parametric oscillator
About: Parametric oscillator is a research topic. Over the lifetime, 5836 publications have been published within this topic receiving 95631 citations. The topic is also known as: Parametric excitation.
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TL;DR: In this paper, the authors present a control-theoretic analysis of a two-level atom coupled with a quantum harmonic oscillator, and show that, by applying external fields with just two resonant frequencies, any desired unitary operator can be generated.
Abstract: We present a control-theoretic analysis of a system consisting of a two-level atom coupled with a quantum harmonic oscillator. We show that, by applying external fields with just two resonant frequencies, any desired unitary operator can be generated.
28 citations
TL;DR: In this paper, the exact solution to Schrodinger's equation for a three-dimensional harmonic oscillator confined by two impenetrable walls is presented, and the energy levels of this system are obtained as a function of wall separation as well as distance of the center of the oscillator to the walls.
Abstract: The exact solution to Schrodinger’s equation for a three‐dimensional harmonic oscillator confined by two impenetrable walls is presented. The energy levels of this system are obtained as a function of wall separation as well as distance of the center of the oscillator to the walls. The force exerted by the walls on the oscillator is also evaluated, showing a classical behavior.
28 citations
TL;DR: In this paper, a vertical, flexible, and submerged cylinder was used to investigate fundamental aspects of risers dynamics subjected to harmonic excitation at the top of the cylinder, and a simple Galerkin projection applied for modal decomposition, combined with standard Mathieu chart analysis, led to the identification of parametric resonances.
Abstract: Experiments with a vertical, flexible, and submerged cylinder were carried out to investigate fundamental aspects of risers dynamics subjected to harmonic excitation at the top. The flexible model was designed aiming a high level of dynamic similarity with a real riser. Vertical motion, with amplitude of 1% of the unstretched length, was imposed with a device driven by a servomotor. Responses to distinct exciting frequency ratios were investigated, namely, ft:fN,1 = 1:3; 1:1; 2:1, and 3:1. Cartesian coordinates of 43 monitored points positioned all along the span were experimentally acquired by using an optical tracking system. A simple Galerkin's projection applied for modal decomposition, combined with standard Mathieu chart analysis, led to the identification of parametric resonances. A curious finding is that the Mathieu instability may simultaneously occur in more than one mode, leading to interesting dynamic behaviors, also revealed through standard power spectra analysis and displacement scalograms.
28 citations
TL;DR: In this paper, a set-up is used to observe the motion of a mercury layer on a substrate located in a solenoidal coil supplied with low-frequency alternating electric currents.
Abstract: New types of electromagnetic parametric instability have been observed at the periphery of the free surface of a liquid metal pool in the presence of a low-frequency magnetic field. An experimental set-up is used to observe the motion of a mercury layer on a substrate located in a solenoidal coil supplied with low-frequency alternating electric currents. The Lorentz body forces produced are mainly oscillatory and generate motion in the liquid. Various regular and irregular free-surface patterns are observed. Two-dimensional stability analysis shows that axisymmetric waves are directly forced by the electromagnetic forces while azimuthal waves are the result of instability. The experimental stability diagram exhibits 'tongues' as already observed for parametric resonance instability. For high magnetic field strengths, the free-surface patterns become highly unstructured. High-amplitude 'fingers' as well as solitary waves are observed. Measurements of the deformation observed on photographs are compared with rough theoretical estimates
28 citations
TL;DR: In this article, the interaction of localized parametric pumping with spin waves of different amplitudes, propagating in a ferromagnetic nanowire, is studied analytically and by micromagnetic simulations.
Abstract: The interaction of a localized parametric pumping with spin waves of different amplitudes, propagating in a ferromagnetic nanowire, is studied analytically and by micromagnetic simulations. It is shown that parametric amplification of spin waves by localized pumping becomes less efficient with an increase in the spin wave amplitude due to the influence of nonlinear 4-magnon processes. In a certain range of spin wave amplitudes, the parametric amplifier acts as a stabilizer of the spin wave amplitude, as its action significantly reduces the spread of the spin wave amplitude in the vicinity of a certain mean value. The stabilization effect becomes more pronounced for higher pumping strength and larger relative lengths of the pumping localization region, compared to the spin wave mean free path. In contrast, the use of relatively short pumping localization regions allows one to efficiently amplify large-amplitude nonlinear spin waves.
28 citations