arXiv subjects

P. V. E. McClintock

Publications and source records attributed to P. V. E. McClintock.

40 records · Page 3Linked to original sources

arXiv1998

Non-Appearance of Vortices in Fast Mechanical Expansions of Liquid 4He Through the Lambda Transition

A new experiment has been performed to study the formation of topological defects (quantized vortices) during rapid quenches of liquid 4He through the superfluid transition, with particular care taken to minimise vortex creation via conventional hydrodynamic flow processes. It is found that the generated vortices, if any, are being produced at densities at least two orders of magnitude less than might be expected on the basis of the Kibble-Zurek mechanism.

cond-mat.soft↗

arXiv1997

Experiments on Critical Phenomena in a Noisy Exit Problem

We consider noise-driven exit from a domain of attraction in a two-dimensional bistable system lacking detailed balance. Through analog and digital stochastic simulations, we find a theoretically predicted bifurcation of the most probable exit path as the parameters of the system are changed, and a corresponding nonanalyticity of the activation energy. We also investigate the extent to which the bifurcation is related to the local breaking of time-reversal invariance.

physics.data-an↗

arXiv1993

High Frequency Stochastic Resonance in Periodically Driven Systems

High frequency stochastic resonance (SR) phenomena, associated with fluctuational transitions between coexisting periodic attractors, have been investigated experimentally in an electronic model of a single-well Duffing oscillator bistable in a nearly resonant field of frequency $ω_F$. It is shown that, with increasing noise intensity, the signal/noise ratio (SNR) for a signal due to a weak trial force of frequency $Ω\sim ω_F$ at first decreases, then {\it increases}, and finally decreases again at higher noise intensities: behaviour similar to that observed previously for conventional (low frequency) SR in systems with static bistable potentials. The stochastic enhancement of the SNR of an additional signal at the mirror-reflected frequency $\vert Ω- 2 ω_F \vert$ is also observed, in accordance with theoretical predictions. Relationships with phenomena in nonlinear optics are discussed.

chao-dyn↗

arXiv1993

Stochastic Resonance

Stochastic resonance (SR) - a counter-intuitive phenomenon in which the signal due to a weak periodic force in a nonlinear system can be {\it enhanced} by the addition of external noise - is reviewed. A theoretical approach based on linear response theory (LRT) is described. It is pointed out that, although the LRT theory of SR is by definition restricted to the small signal limit, it possesses substantial advantages in terms of simplicity, generality and predictive power. The application of LRT to overdamped motion in a bistable potential, the most commonly studied form of SR, is outlined. Two new forms of SR, predicted on the basis of LRT and subsequently observed in analogue electronic experiments, are described.

chao-dyn↗