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We report an experimental realization of a modified counterfactual communication protocol that eliminates the dominant environmental trace left by photons passing through the transmission channel. Compared to Wheeler’s criterion for inferring past particle paths, as used in prior protocols, our trace criterion provides stronger support for the claim of the counterfactuality of the communication. We verify the lack of trace left by transmitted photons via tagging the propagation arms of an interferometric device by distinct frequency-shifts and finding that the collected photons have no frequency shift which corresponds to the transmission channel. As a proof of principle, we counterfactually transfer a quick response code image with sufficient fidelity to be scanned with a cell phone. 

Stimulated Raman projection tomography is a label-free volumetric chemical imaging technology allowing three-dimensional (3D) reconstruction of chemical distribution in a biological sample from the angle-dependent stimulated Raman scattering projection images. However, the projection image acquisition process requires rotating the sample contained in a capillary glass held by a complicated sample rotation stage, limiting the volumetric imaging speed, and inhibiting the study of living samples. Here, we report a tilt-angle stimulated Raman projection tomography (TSPRT) system which acquires angle-dependent projection images by utilizing tilt-angle beams to image the sample from different azimuth angles sequentially. The TSRPT system, which is free of sample rotation, enables rapid scanning of different views by a tailor-designed four-galvo-mirror scanning system. We present the design of the optical system, the theory, and calibration procedure for chemical tomographic reconstruction. 3D vibrational images of polystyrene beads and C. elegans are demonstrated in the C-H vibrational region.

 

Wave runup is an important process due to its effects on sediment transport and its role in coastal hazards. Despite decades of research on this topic, much uncertainty still exists in the estimation and prediction of runup. A recent numerical study has shown that there is appreciable variability in runup among wave groups on a dissipative beach due to sequencing of bichromatic waves and the resulting merging of bores. The current work further explores, in a highly controlled laboratory setting, runup variability due to wave sequencing. It is found that considerable runup variability exists among wave groups, and that this variability can differ greatly depending on the incident wave conditions. The observations suggest that the largest runup results from a higher number of bore merging events and involves a carrier wave that is positioned behind the infragravity wave crest, while the smallest runup results from a lower number of bore merging events and a carrier wave in front of the infragravity wave. A relationship is presented between runup variability and wave height, wave length, and the number of waves in a group. It is also found that an increase in runup variability is associated with an increase, at the first bore merging event, in the surface elevation at the crest of the carrier wave. Runup variability is also larger when the first bore merging event occurs further offshore, and when the local surface slope of the infragravity wave is higher.