An array of parallel (horizontal) waveguides can mimic a superfluid moving through a pipe with an obstacle at the entrance (green dots, exaggerated in size). The light intensity inside the array of waveguides is shown as rainbow colors (black: no light; yellow: highest intensity). The top panel shows the superfluid motion of light, which keeps its overall shape even after it has passed the obstacle.The bottom panel shows the light moving through the array like a dissipative fluid, for which an obstacle clearly changes the shape of the flow.
Picture: Patricio Leboeuf.
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