15,438 research outputs found
Synchronous control of dual-channel all-optical multi-state switching
We have experimentally observed optical multistabilities (OMs) simultaneously
on both the signal and generated Stokes fields in an optical ring cavity with a
coherently-prepared multilevel atomic medium. The two observed OMs, which are
governed by different physical processes, are coupled via the multilevel atomic
medium and exhibit similar threshold behaviors. By modulating the cavity input
(signal) field with positive or negative pulses, dual-channel all-optical
multi-state switching has been realized and synchronously controlled, which can
be useful for increasing communication and computation capacities
Bubble Nucleation of Spatial Vector Fields
We study domain-walls and bubble nucleation in a non-relativistic vector
field theory with different longitudinal and transverse speeds of sound. We
describe analytical and numerical methods to calculate the orientation
dependent domain-wall tension, . We then use this tension to
calculate the critical bubble shape. The longitudinally oriented domain-wall
tends to be the heaviest, and sometime suffers an instability. It can
spontaneously break into zigzag segments. In this case, the critical bubble
develops kinks, and its energy, and therefore the tunneling rate, scales with
the sound speeds very differently than what would be expected for a smooth
bubble.Comment: version 4, correction in the citation
Molecular hydrodynamics of the moving contact line in two-phase immiscible flows
The ``no-slip'' boundary condition, i.e., zero fluid velocity relative to the
solid at the fluid-solid interface, has been very successful in describing many
macroscopic flows. A problem of principle arises when the no-slip boundary
condition is used to model the hydrodynamics of immiscible-fluid displacement
in the vicinity of the moving contact line, where the interface separating two
immiscible fluids intersects the solid wall. Decades ago it was already known
that the moving contact line is incompatible with the no-slip boundary
condition, since the latter would imply infinite dissipation due to a
non-integrable singularity in the stress near the contact line. In this paper
we first present an introductory review of the problem. We then present a
detailed review of our recent results on the contact-line motion in immiscible
two-phase flow, from MD simulations to continuum hydrodynamics calculations.
Through extensive MD studies and detailed analysis, we have uncovered the slip
boundary condition governing the moving contact line, denoted the generalized
Navier boundary condition. We have used this discovery to formulate a continuum
hydrodynamic model whose predictions are in remarkable quantitative agreement
with the MD simulation results at the molecular level. These results serve to
affirm the validity of the generalized Navier boundary condition, as well as to
open up the possibility of continuum hydrodynamic calculations of immiscible
flows that are physically meaningful at the molecular level.Comment: 36 pages with 33 figure
- …