Topical phenomena in high-energy physics related to collision experiments of heavy nuclei (”Little Bang”) and early universe cosmology (”Big Bang”) involve far-from-equilibrium dynamics described by quantum field theory. One example concerns the role of plasma instabilities for the process of thermalization in heavy-ion collisions. The reheating of the early universe after inflation may exhibit...

Dynamical instabilities in a Rb F=1 spinor Bose-Einstein condensate are used as a parametric amplifier of quantum spin fluctuations. We demonstrate the spectrum of this amplifier to be tunable, in quantitative agreement with theory. We quantify the microscopic spin fluctuations of the initially paramagnetic condensate by applying this amplifier and measuring the resulting macroscopic magnetizat...

We analyze the dynamical stability of hydrodynamical flows in the equatorial plane of a thin axisymmetric accretion disk in close binary systems. The periodic tidal forces of the companion star induce parametric instabilities, which are characterized by the Floquet exponent. We propose that the onset of superhumps can be understood in this context. Comparing our model with well-known systems le...

In contrast to conventional expectations based on the stability of steady shear flows, elementary time-periodic stratified flows that are unstable at arbitrarily large Richardson numbers are presented here. The fundamental instability is a parametric one with twice the period of the basic state. This instability spontaneously generates local shears on buoyancy time scales near a specific angle ...

We employ the Q representation to study the non-classical correlations that are present from below to above-threshold in the degenerate optical parametric oscillator. Our study shows that such correlations are present just above threshold, in the regime in which stripe patterns are formed, but that they also persist further above threshold in the presence of spatially disordered structures. PAC...

The geometric aspects of HF-generated Langmuir turbulence in the ionosphere and its detection by radars are theoretically discussed in a broad approach, including local modelling (damped and driven Zakharov system), basic parametric instabilities, polarization and strength of the driving electric field, and radar configurations. Selected examples of numerical results from the local model are pr...

We present experimental results on the suppression of a complete Raman cascade in a holey fiber by using gain competition with parametric processes. The modulation instabilities which strongly affect the stimulated Raman scattering (SRS) gain are induced by two pump wavelengths (532 nm, 1064 nm) placed far and quasi symmetrically on each side of the zero dispersion wavelength (ZDW) of the fiber...

Abstract We present observations of microwave diagnostics damage in three discharges employing third-harmonic X-mode electron cylcotron resonance heating (ECRH) at the ASDEX Upgrade tokamak. In all cases, is explainable terms a parametric decay instability (PDI), where an ECRH wave decays to two trapped upper hybrid (UH) waves near half frequency, followed by secondary instabilities, which gene...