5,366 research outputs found
Granular rheology: measuring boundary forces with laser-cut leaf springs
In granular physics experiments, it is a persistent challenge to obtain the
boundary stress measurements necessary to provide full a rheological
characterization of the dynamics. Here, we describe a new technique by which
the outer boundary of a 2D Couette cell both confines the granular material and
provides spatially- and temporally- resolved stress measurements. This key
advance is enabled by desktop laser-cutting technology, which allows us to
design and cut linearly-deformable walls with a specified spring constant. By
tracking the position of each segment of the wall, we measure both the normal
and tangential stress throughout the experiment. This permits us to calculate
the amount of shear stress provided by basal friction, and thereby determine
accurate values of .Comment: 4 pages, 5 figures, powder and grains 2017 conferenc
Fast cooling of trapped ions using the dynamical Stark shift gate
A laser cooling scheme for trapped ions is presented which is based on the
fast dynamical Stark shift gate, described in [Jonathan etal, PRA 62, 042307].
Since this cooling method does not contain an off resonant carrier transition,
low final temperatures are achieved even in traveling wave light field. The
proposed method may operate in either pulsed or continuous mode and is also
suitable for ion traps using microwave addressing in strong magnetic field
gradients.Comment: 4 pages 5 figure
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