1,609 research outputs found
All-atomic source of squeezed vacuum with full pulse-shape control
We report on the generation of pulses of a low-frequency squeezed vacuum with
noise suppression >2 dB below the standard quantum limit in a hot resonant 87
Rb vapor with polarization self-rotation. We demonstrate the possibility to
precisely control the temporal profile of the squeezed noise quadrature by
applying a calibrated longitudinal magnetic field, without degrading the
maximum amount of squeezing
Persistence-driven durotaxis: Generic, directed motility in rigidity gradients
Cells move differently on substrates with different elasticities. In
particular, the persistence time of their motion is higher on stiffer
substrates. We show that this behavior will result in a net transport of cells
directed up a soft-to-stiff gradient. Using simple random walk models with
controlled persistence and stochastic simulations, we characterize this
propensity to move in terms of the durotactic index measured in experiments. A
one-dimensional model captures the essential features of this motion and
highlights the competition between diffusive spreading and linear, wavelike
propagation. Since the directed motion is rooted in a non-directional change in
the behavior of individual cells, the motility is a kinesis rather than a
taxis. Persistence-driven durokinesis is generic and may be of use in the
design of instructive environments for cells and other motile, mechanosensitive
objects.Comment: 5 pages, 4 figure
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