Researchers announce photon-phonon breakthrough

New research by a City College of New York team has uncovered a novel way to combine two different states of matter. 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. 

The study utilized topological photonics, an emergent direction in photonics which leverages fundamental ideas of the mathematical field of topology about conserved quantities—topological invariants—that remain constant when altering parts of a geometric object under continuous deformations. One of the simplest examples of such invariants is number of holes, which, for instance, makes donut and mug equivalent from the topological point of view. The topological properties endow photons with helicity, when photons spin as they propagate, leading to unique and unexpected characteristics, such as robustness to defects and unidirectional propagation along interfaces between topologically distinct materials. Thanks to interactions with vibrations in crystals, these helical photons can then be used to channel infrared light along with vibrations. 

The implications of this work are broad, in particular allowing researchers to advance Raman spectroscopy, which is used to determine vibrational modes of molecules. The research also holds promise for vibrational spectroscopy—also known as infrared spectroscopy—which measures the interaction of infrared radiation with matter through absorption, emission, or reflection. This can then be utilized to study and identify and characterize chemical substances.

«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 them around defects and sharp corners was impossible before.»

The new methodology can also implement directional radiative heat transfer, a form of energy transfer during which heat is dissipated through electromagnetic waves. 

«We can create channels of arbitrary shape for this form of hybrid light and matter excitations to be guided along within a two-dimensional material we created,» added Dr. Sriram Guddala, postdoctoral researcher in Prof. Khanikaev’s group and the first author of the manuscript. «This method also allows us to switch the direction of propagation of vibrations along these channels, forward or backward, simply by switching polarizations handedness of the incident laser beam. Interestingly, as the phonon-polaritons propagate, the vibrations also rotate along with the electric field. This is an entirely novel way of guiding and rotating lattice vibrations, which also makes them helical.»

Entitled «Topological phonon-polariton funneling in midinfrared metasurfaces,» the study appears in the journal Science. 

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The ‘X17’ particle: Scientists may have discovered the fifth force of nature

A new paper suggests that the mysterious X17 subatomic particle is indicative of a fifth force of nature.

Physicists have long known of four fundamental forces of nature: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. 

Now, they might have evidence of a fifth force. 

The discovery of a fifth force of nature could help explain the mystery of dark matter, which is proposed to make up around 85 percent of the universe’s mass. It could also pave the way for a unified fifth force theory, one that joins together electromagnetic, strong and weak nuclear forces as «manifestations of one grander, more fundamental force,» as theoretical physicist Jonathan Feng put it in 2016.

The new findings build upon a study published in 2016 that offered the first hint of a fifth force.

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Aqua-Fi: Underwater WiFi developed using LEDs and lasers

Aquatic internet that sends data through light beams could enable divers to instantly transmit footage from under the sea to the surface.

The internet is an indispensable communication tool, connecting tens of billions of devices worldwide, and yet we struggle to connect to the web from under water. «People from both academia and industry want to monitor and explore underwater environments in detail,» explains the first author, Basem Shihada. Wireless internet under the sea would enable divers to talk without hand signals and send live data to the surface.

Underwater communication is possible with radio, acoustic and visible light signals. However, radio can only carry data over short distances, while acoustic signals support long distances, but with a very limited data rate. Visible light can travel far and carry lots of data, but the narrow light beams require a clear line of sight between the transmitters and receivers.

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Filmada por primera vez la observación cuántica

La naturaleza duda antes de que el gato de Schrödinger aparezca vivo a muerto.

Los científicos han filmado lo que pasa cuando un observador se asoma al mundo cuántico: las dos probabilidades superpuestas dudan en el momento de elegir entre la vida y la muerte del gato, antes de que Schrödinger abra la caja.

Ion de estroncio atrapado en un campo eléctrico. La medición en el ion dura solo una millonésima de segundo… ¡y ha sido filmada! Crédito: F. Pokorny et al.
Un equipo de investigadores de Suecia, Alemania y España (Universidad de Sevilla) ha conseguido por primera vez filmar lo que pasa cuando un observador se asoma al mundo cuántico.

Es como decir, metafóricamente, que una cámara ha grabado el momento en el que Schrödinger destapa la caja y encuentra al gato vivo o muerto.

Según un ejemplo imaginado por el físico Erwin Schrödinger en 1935, si tenemos un gato dentro de una caja en la que hay alimento y veneno, el dueño del gato es el que decide su suerte al abrir la caja: estará vivo o muerto según lo que el observador quiera encontrar.

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The Kinetic energy form a single raindrop can enlight 100 small led bulbs







A single raindrop can now power 100 small LED light bulbs, effectively setting a new milestone for energy-harvesting technologies, scientists have reported.

The droplet-based electricity generator has a high energy-conversion efficiency and power density thousand times bigger than its counterparts.

The developers hope the tech will help to tackle the world energy crisis by providing new ways of making use of the environmental energy around us in water and rain.

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