Light, which travels at a speed of 300,000 km/sec in a vacuum, can be slowed down and even stopped completely by methods that involve trapping the light inside crystals or ultracold clouds of atoms. Now in a new study, researchers have theoretically demonstrated a new way to bring light to a standstill: they show that light stops at "exceptional points," which are points at which two light modes come together and coalesce, in waveguides that have a certain kind of symmetry.
Unlike most other methods that are used to stop light, the new method can be tuned to work with a wide range of frequencies and bandwidths, which may offer an important advantage for future slow-light applications.
The researchers, Tamar Goldzak and Nimrod Moiseyev at the Technion – Israel Institute of Technology, along with Alexei A. Mailybaev at the Instituto de Matemática Pura e Aplicada (IMPA) in Rio de Janeiro, have published a paper on stopping light at exceptional points in a recent issue of Physical Review Letters.
This is going to be amazing technology once mapped out by AI. As AI is already 3d printing aerodynamic objects we never dreamed of. They will also be able to make objects with exceptional points placed strategically... We might get to view a photon of light trapped against another one within one of the exceptional points!!!
The technique described in this Jan. 3 paper doesn't rely on supercooled atoms or imprinting light. Instead, it relies on some funny quirks of how waves — including light waves — behave under the unusual circumstances of "exceptional points."
An exceptional point is a place where two complex wavelength patterns that mirror one another meet — merging into one pattern or the other, depending on which way they are traveling.
Let's break that down:
You might have heard that light is a wave, and there's a good chance you imagine it as a fairly simple wave, like this:
But the reality is, waves in the real world — whether they're made of light, sound or quantum vibrations — are much richer and more complex three-dimensional shapes that change constantly, according to the properties of the container they're moving through.
By tuning the properties of the container just so, scientists have figured out how to collapse one complex wave into its mirror twin. This phenomenon happens at exceptional points, or points around which waves show exceptionally quirky behaviors. Fire a beam of light and its mirror twin through the point one way, and both will emerge looking like the original beam of light. Fire them through the other way, and both will emerge looking like the mirror wave.
In this paper, the scientists showed that, theoretically, the properties of the exceptional point and the beams of light could be tuned in such a way that the light would stop moving entirely at this exceptional point. Change the properties and light beams again, and the light would continue on its merry way.
For a long time, scientists thought exceptional points were purely theoretical concepts. But back in 2010, researchers were able to build one in the real world by firing microwaves through a specially built metal box, causing the wave patterns to flip from one mode to another.
Researchers haven't yet built a light-stopping exceptional point in the real world — and it remains to be seen whether anyone will. In a statement from the team behind the light-stopping exceptional points paper, the researchers said that their next step is to figure out whether similar exceptional points could stop other kinds of waves, like sound, in their tracks.
Down the road, the team wrote in this paper, they expect the up-tick in research into exceptional points to help solve important problems in quantum mechanics, and point the way toward new technologies that rely on bending and shaping waves.
Source:
I copy and pasted a lot of this from a science site that I'm sure Cheetahbot will link below :P
