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A surprising connection between exotic states of matter and a precursor of El Nino

Venaille The last decades have witnessed a tremendous explosion in the use of topology in condensed matter physics, through the discovery of  exotic states of matter that are insulating in the bulk, but good conductors at the edge of a sample.These materials support unidirectional electronic edge waves  that propagate without back-scattering in the presence of impurities. These unidirectional waves are said to be topologically protected, because they owe their existence to a topological invariant encoded in the fluctuation spectrum of bulk electronic waves. This bulk invariant guarantees the existence of unidirectional edge states when parameters are varied, when boundary properties are changed, and when disorder is added.
Physicists realized recently that topological protection applies to virtually all areas of physics from photonics, to cold atoms and even classical mechanical systems. We will show that Eastward propagating heat waves involved in El Niño phenomenon also have a topological origin. We will relate their topological properties to the dual role of Coriolis force, that breaks time-reversal symmetry, and changes sign at the equator thereby trapping waves at the boundary between the two hemispheres.