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For one of the first times, topological photons—light—has been combined with lattice vibrations, also known as phonons, to manipulate their propagation in a robust and controllable way. "We coupled helical photons with lattice vibrations in hexagonal boron nitride, creating a new hybrid matter referred to as phonon-polaritons," said Alexander Khanikaev, lead author and physicist with affiliation in CCNY's Grove School of Engineering. "It is half light and half vibrations. Since infrared light and lattice vibrations are associated with heat, we created new channels for propagation of light and heat together. Typically, lattice vibrations are very hard to control, and guiding...

The researchers' lab-grown black hole was made of a flowing gas of approximately 8,000 rubidium atoms cooled to nearly absolute zero and held in place by a laser beam. They created a mysterious state of matter, known as a Bose-Einstein Condensate (BEC), which allows thousands of atoms to act together in unison as though they were a single atom. Using a second laser beam, the team created a cliff of potential energy, which caused the gas to flow like water rushing down a waterfall, thereby creating an event horizon where one half of the gas was flowing faster than the...

Sound has negative mass, and all around you it's drifting up, up and away — albeit very slowly. That's the conclusion of a paper submitted on July 23 to the preprint journal arXiv, and it shatters the conventional understanding that researchers have long had of sound waves: as massless ripples that zip through matter, giving molecules a shove but ultimately balancing any forward or upward motion with an equal and opposite downward motion. That's a straightforward model that will explain the behavior of sound in most circumstances, but it's not quite true, the new paper argues. A phonon — a...