Recently, there has been much interest in using lubricated flat and
nano-/micro-structured surfaces to achieve extreme liquid-repellency: any
foreign droplet immiscible with the underlying lubricant layer was shown to
slide off at a small tilt angle $<$ 5$^{\circ}$. This behavior was hypothesized
to arise from a thin lubricant overlayer film sandwiched between the droplet
and solid substrate, but this has not been observed experimentally. Here, using
confocal optical interferometry, we are able to visualize the intercalated film
under both static and dynamic conditions. We further demonstrate that the
lubricant flow entrained by droplet motion can transform a partially dewetted
film into a continuous layer, by generating a sufficient hydrodynamic force to
lift the droplet over the solid substrate. The droplet is therefore
oleoplaning, akin to tires hydroplaning on a wet road, with minimal dissipative
force (down to 0.1 $\mu$N for 1 $\mu$l droplet when measured using a cantilever
force sensor) and no contact line pinning. The techniques and insights
presented in this study will inform future work on the fundamentals of wetting
for lubricated surfaces and enable their rational design
Polaritons formed by the coupling of light and material excitations enable light-matter interactions at the nanoscale beyond what is currently possible with conventional optics. However, novel techniques are required to control the propagation of polaritons at the nanoscale and to implement the first practical devices. Here we report the experimental realization of polariton refractive and meta-optics in the mid-infrared by exploiting the properties of low-loss phonon polaritons in isotopically pure hexagonal boron nitride interacting with the surrounding dielectric environment comprising the low-loss phase change material Ge3Sb2Te6. We demonstrate rewritable waveguides, refractive optical elements such as lenses, prisms, and metalenses, which allow for polariton wavefront engineering and sub-wavelength focusing. This method will enable the realization of programmable miniaturized integrated optoelectronic devices and on-demand biosensors based on high quality phonon resonators.
Many quantum key distribution systems employ a laser followed by an optical attenuator to prepare weak coherent states in the source. Their mean photon number must be pre-calibrated to guarantee the security of key distribution. Here we experimentally show that this calibration can be broken with a high-power laser attack. We have tested four fiber-optic attenuator types used in quantum key distribution systems, and found that two of them exhibit a permanent decrease in attenuation after laser damage. This results in higher mean photon numbers in the prepared states and may allow an eavesdropper to compromise the key.
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