Category Physics

Leaky-Wave Metasurfaces: A Perfect Interface between Free-Space and Integrated Optical Systems

Six holographic images produced by leaky-wave metasurfaces
Left two figures: Two holographic images produced by a leaky-wave metasurface at two different distances from the device surface. Right four figures: Four distinct holographic images produced by a single leaky-wave metasurface at two different distances from the device surface and at two orthogonal polarization states. Credit: Heqing Huang, Adam Overvig, and Nanfang Yu/Columbia Engineering

Researchers at Columbia Engineering have developed a new class of integrated photonic devices – “leaky-wave metasurfaces” – that can convert light initially confined in an optical waveguide to an arbitrary optical pattern in free space...

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Training Machines to Learn more like humans do

Training machines to learn more like humans do
Schematic illustration of the representation of a discrete video sequence becoming progressively straighter as information is processed through a visual processing pipeline, starting from the highly nonlinear trajectory of typical video frames in pixel space. Credit: Anne Harrington, Vasha DuTell, Ayush Tewari, Mark Hamilton, Simon Stent, Ruth Rosenholtz and William T. Freeman, https://openreview.net/pdf?id=4cOfD2qL6T

Imagine sitting on a park bench, watching someone stroll by. While the scene may constantly change as the person walks, the human brain can transform that dynamic visual information into a more stable representation over time. This ability, known as perceptual straightening, helps us predict the walking person’s trajectory.

Unlike humans, computer vision models don’t t...

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Silicon Heterojunction Solar Cells with up to 26.81% Efficiency

Silicon heterojunction solar cells with up to 26.81% efficiency
Electrical performance of LONGi SHJ solar cells with different designs. a, Diagram of LONGi SHJ solar cells. b,c, Experimental (Exp.) and fitted (Fit.) J–V curves for the p-a-Si:H cell (b, cell 1 in Fig. 1) and the p-nc-Si:H cell (c, cell 2 in Fig. 1). The fitted curves are derived from the Quokka2 simulations (Methods). Intrinsic J–V curves are obtained according to the Richter et al. model of intrinsic recombination with photon recycling (photon recycling coefficient of 0.6). The black arrows between the Suns–VOC and light J–V curves indicate the series resistance of solar cells. Insets: the PV parameters certified by ISFH. d, PLA and corresponding RS at the MPP derived by fitting J–V curves in b and c; rec, recombination...
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The Influence of AI on Trust in Human Interaction

Professorerna Jonas Ivarsson och Oskar Lindwall
Jonas Ivarsson and Oskar Lindwall

As AI becomes increasingly realistic, our trust in those with whom we communicate may be compromised. Researchers at the University of Gothenburg have examined how advanced AI systems impact our trust in the individuals we interact with.

In one scenario, a would-be scammer, believing he is calling an elderly man, is instead connected to a computer system that communicates through pre-recorded loops. The scammer spends considerable time attempting the fraud, patiently listening to the “man’s” somewhat confusing and repetitive stories. Oskar Lindwall, a professor of communication at the University of Gothenburg, observes that it often takes a long time for people to realize they are interacting with a technical system.

He has, in collaboration with...

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