Non-linear acoustic coupling of modes in accretion disks allows a parametric resonance between epicyclic motions. In black hole disks, such a resonance first occurs, and is strongest, when the radial and vertical epicyclic frequencies are approximately in a 2:3 ratio, in agreement with the 300 and 450 Hz frequencies reported in GRO J1655-40 and the 184 and 276 Hz frequencies reported in XTE J15...

Parametric enhancement of the appearance probability of the neutrino oscillation under the inhomogeneous matter is studied. Fourier expansion of the matter density profile leads to a simple resonance condition and manifests that each Fourier mode modifies the energy spectrum of oscillation probability at around the corresponding energy; below the MSW resonance energy, a large-scale variation mo...

2014 This paper reports the four-photon ionization of caesium atoms when the laser frequency is tuned through the resonant three-photon transition 6S ~ 6F. This experiment was performed by using a tunable-wavelength bandwidth-limited subnanosecond laser pulse at 1.06 03BCm, in the 108-109 W.cm-2 laser intensity range. Pulse widths of 1.5 ns, 50 ps, and 15 ps were used. The resonant character of...

We demonstrate a novel technique for direct measurement of the oscillation frequency in an optical-tweezers trap. The technique uses the phenomenon of parametric resonance in an oscillator when the stiffness of the trapping potential is modulated. The trapped particle is a strongly damped oscillator; hence, the signature of parametric resonance is not an increase in the amplitude but an increas...

We demonstrate that cosmological perturbations can undergo amplification by parametric resonance during the preheating period following inflation, even on scales larger than the Hubble radius, without violating causality. A unified description of gravitational and matter fluctuations is crucial in order to determine the strength of the instability. To extract specific signatures of the oscillat...

We investigate the end of the inflationary period in the recently proposed scenario of locked inflation, and consider various constraints arising from density perturbations, loop corrections, parametric resonance and defect formation. We show that in a scenario where there is one long period of locked inflation, it is not possible to satisfy all of these constraints without having a period of s...

Explosive particle production due to parametric resonance is a crucial feature of reheating in in ationary cosmology. Coherent oscillations of the in aton eld act as a periodically varying mass in the evolution equation for matter elds which couple to the in aton. This in turn results in the parametric resonance instability. Thermal and quantum noise will lead to a nonperiodic perturbation in t...

Nonlinear kinetic inductance in a high Q superconducting coplanar waveguide microresonator can cause a bifurcation of the resonance curve. Near the critical pumping power and frequency for bifurcation, large parametric gain is observed for signals in the frequency band near resonance. We show experimental results on signal and intermodulation gain which are well described by a theory of the par...

Aiming at increasing the apparent bunchlength and hence the beam life time in electrons storage rings, RF phase modulation near one parametric resonance has been experimentally investigated. Since the eventual benefit of this technique depends greatly on the ring parameters, we studied the effect of such a modulation for different RF parameters on the longitudinal emittance. Theoritical predict...

In this work, parametric noise squeezing and parametric resonance are realized through the use of an electronic feedback circuit to excite a microcantilever with a signal proportional to the product of the microcantilever's displacement and a harmonic signal. The cantilever's displacement is monitored using an optical lever technique. By adjusting the gain of an amplifier in the feedback circui...