Hawking radiation - how fast moving structures can generate quanta of light

What is it about?

Light is controlled by the refractive index of the medium through which it flows. Of increasing interest are materials in which the index changes rapidly in both space and time. One example might be a wave-like modulation of the index which appears to move but without any material motion, rather like a wave on the ocean. This means that it can move with any velocity unrestricted by the speed of light and spectacular results appear when the velocities of light and grating coincide: any incident light is captured and compressed into short hot pulses. And even if no light is present initially, these fast moving structures will spontaneously emit flashes of light. This is a quantum mechanical effect closely analogous to the generation of Hawking radiation in a black hole.

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Photo by Ben Collins on Unsplash

Photo by Ben Collins on Unsplash

Why is it important?

Metamaterials derive their properties principally from their internal structure rather than their chemical composition. The addition of structure to the lexicon of variables has enabled the creation of material properties not found in nature, such as negative refractive indices. These materials now appear in many optical and electrical devices. For example they will be an integral part of 6G the next generation cell-phone network. Missing until recently has been the ability to add the time dimension to structural variables. Not only will this empower the design of new devices just as the static version does, but the ability to stimulate quantum processes links metamaterials to the rich fields of the quantum world such as quantum computation. Furthermore, as with any new area of research, fundamental theoretical issues emerge some of which we address in our paper.

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