4,056 research outputs found
Observation of dispersive wave emission by temporal cavity solitons
We examine a coherently-driven, dispersion-managed, passive Kerr fiber ring
resonator and report the first direct experimental observation of dispersive
wave emission by temporal cavity solitons. Our observations are in excellent
agreement with analytical predictions and they are fully corroborated by
numerical simulations. These results lead to a better understanding of the
behavior of temporal cavity solitons under conditions where higher-order
dispersion plays a significant role. Significantly, since temporal cavity
solitons manifest themselves in monolithic microresonators, our results are
likely to explain the origins of spectral features observed in broadband Kerr
frequency combs.Comment: 4 pages, 3 figure
Murdoch and the End of Ideology
Iris Murdoch had a lifelong interest in politics and she reflected upon the nature of ideology throughout her career. What she had to say on the subject developed during her career and relates to general academic discussions on the nature of ideology. At the outset of her career she was a committed socialist. She recognised that political ideology was in retreat after the Second World War but sought to contribute to socialist ideology. Later in her career she became sceptical of radical utopian ideologies, including socialism and developed a theory of politics that prioritised safeguarding individual liberty and security. However, she imagined that political thought would continue to develop and offer new possibilities and so she did not call for the end of ideology but continued to value political ideas
Understanding the production of dual BEC with sympathetic cooling
We show, both experimentally and theoretically, that sympathetic cooling of
Rb atoms in the state by evaporatively cooled atoms in the
state can be precisely controlled to produce dual or single
condensate in either state. We also study the thermalization rate between two
species. Our model renders a quantitative account of the observed role of the
overlap between the two clouds and points out that sympathetic cooling becomes
inefficient when the masses are very different. Our calculation also yields an
analytical expression of the thermalization rate for a single species.Comment: 3 figure
Observations of spatiotemporal instabilities in the strong-driving regime of an AC-driven nonlinear Schr\"odinger system
Localized dissipative structures (LDS) have been predicted to display a rich
array of instabilities, yet systematic experimental studies have remained
scarce. We have used a synchronously-driven optical fiber ring resonator to
experimentally study LDS instabilities in the strong-driving regime of the
AC-driven nonlinear Schr\"odinger equation (also known as the Lugiato-Lefever
model). Through continuous variation of a single control parameter, we have
observed a string of theoretically predicted instability modes, including
irregular oscillations and chaotic collapses. Beyond a critical point, we
observe behaviour reminiscent of a phase transition: LDSs trigger localized
domains of spatiotemporal chaos that invade the surrounding homogeneous state.
Our findings directly confirm a number of theoretical predictions, and they
highlight that complex LDS instabilities can play a role in experimental
systems.Comment: 6 pages, 4 figure
- …