Related papers: Parametric Resonance in an Expanding Universe
A non-markovian stochastic model shows the emergence of structures in the medium, a self-organization characterized by a relationship between particle's energy, driven frequency $\omega$ and a frequency of interaction with the medium $\nu$.…
Stimulated emission of two photons is observed experimentally in the parametric amplification process and is compared to a three-photon interference scheme. We find that the underlying physics of stimulated emission is simply the…
We consider the interaction between perturbations in the inflaton and in the metric during the preheating phase in simple inflationary models. By numerically integrating the Einstein field equations we are able to gauge the impact of…
We develop a model for parametric amplification, based on a density matrix approach, which naturally accounts for the peculiarities arising for matter waves: significant depletion and explicit time-dependence of the source state population,…
The early Universe inflation is well known as a promising theory to explain the origin of large scale structure of the Universe, a causal theory for the origin of primordial density fluctuations which may explain the observed density…
After inflation the Universe presumably undergoes a phase of reheating which in effect starts the thermal big bang cosmology. However, so far we have very little direct experimental or observational evidence of this important phase of the…
The propagation of compressional MHD waves is studied for an externally driven system. It is assumed that the combined action of the external sources and sinks of the entropy results in the harmonic oscillation of the entropy (and…
The superpotential method is a reconstruction technique which has proven useful to build exact cosmological solutions. We here employ the superpotential method in order to reconstruct the features necessary for the inflaton potential to…
The power spectrum of the cosmic microwave background from both the {\it Planck} and {\it WMAP} data exhibits a slight dip for multipoles in the range of $l= 10-30$. We show that such a dip could be the result of the resonant creation of…
We report on the use of parametric excitation to coherently manipulate the collective spin state of an atomic vapour at room temperature. Signatures of the parametric excitation are detected in the ground-state spin evolution. These include…
We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multi-field inflationary models by means of lattice simulations. We observe a strong suppression of resonances in the…
We study a conservative system of two nonlinear coupled oscillators. The eigenmodes of the system are thus nonlinearly coupled, and one of them may induce a parametric amplification of the other, called an autoparametric resonance of the…
We study the class of two-field inflationary Universe models \lambda\phi^4/4 + g^2\chi^2\phi^2/2, in which parametric resonance during the initial stages of reheating can lead to an exponential amplification of the amplitude of cosmological…
In this review I consider several different issues related to inflation. I will begin with the wave function of the Universe. This issue is pretty old, but recently there were some new insights based on the theory of the self-reproducing…
We study scalar dark matter production and reheating via renormalizable inflaton couplings, which include both quartic and trilinear interactions. These processes often depend crucially on collective effects such as resonances, backreaction…
Pattern formation of sound is predicted in a driven resonator where subharmonic generation takes place. A model allowing for diffraction of the fields (large-aspect ratio limit) is derived by means of the multiple scale expansions…
High-gain optical parametric amplification is an important nonlinear process used both as a source of coherent infrared light and as a source of nonclassical light. In this work, we experimentally demonstrate an approach to optical…
This paper presents a detailed theoretical review of the amplification process in Josephson Parametric Amplifiers (JPAs), which are crucial for quantum-limited signal amplification in superconducting circuits. The paper begins by outlining…
Optical parametric amplification/oscillation provide a powerful tool for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency {\it down-conversion} process, and thus it can not be…
We introduce a time-dependent perturbation method to calculate the number of created particles in a 1D cavity with an oscillating wall of the frequency $\Omega . $ This method makes it easy to find the dominant part of the solution which…