A new way to combine two different states of matter


Scientists at the City College of New York have created a new way of combining two different states of matter. Scientists combined topological photons – light with lattice vibrations, also known as phonons, using this new approach. In doing so, they were able to manipulate their propagation in a robust and controllable manner.

Scientists used topological photonics, an emerging direction in photonics that takes advantage of fundamental ideas in the mathematical field of topology about conserved quantities (topological invariants) that remain constant when changing parts of a geometric object under deformations. continues.

The topological properties give photons helicity as the photons rotate as they propagate, causing exciting and surprising properties, such as robustness to defects and unidirectional propagation and the interfaces between topologically particular materials. Due to the communications with the vibrations in the crystals, these helical photons would then be used to channel infrared light alongside the vibrations.

Alexander Khanikaev, senior author and physicist affiliated with the Grove School of Engineering at CCNY, said: “We coupled helical photons with lattice vibrations in hexagonal boron nitride, creating a new hybrid material called phonon-polaritons. It is half light and half vibration. Since infrared light and network vibrations are associated with heat, we have created new channels to propagate light and heat together. Typically, network vibrations are very difficult to control and guide around faults, and sharp angles were previously impossible. “

This work has a wide range of implications. It could be used to advance Raman spectroscopy. In addition, it shows promise for vibrational spectroscopy, also known as infrared spectroscopy.

Dr Sriram Guddala, postdoctoral researcher in Prof. Khanikaev’s group and first author of the manuscript, said: “We can create arbitrarily shaped channels so that this form of hybrid excitations of light and matter is guided into a two-dimensional material that we have created.”

“This method also allows us to change the direction of vibration propagation along these channels, forward or backward, simply by reversing the manual polarizations of the incident laser beam. Interestingly, as the phonons-polaritons propagate, the vibrations also rotate with the electric field. This is an entirely new way of guiding and rotating network vibrations, which also makes them helical.

The new method of combining two states of matter can also involve directional radiative heat transfer, a form of energy transfer in which heat is dissipated by electromagnetic waves.

Journal reference:
  1. S. Guddala, F. Komissarenko et al. Phonon-polariton topological funnel in mid-infrared metasurfaces. DOI: 10.1126 / science.abj5488

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