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Light ties itself in knots - spontaneously

Beautiful physics

It’s not only possible to get light to tie itself in knots: given the right conditions, it will do so spontaneously, according to a paper published last week in Nature.

El Reg has no possible hope of fully understanding this paper (published in full, an emerging trend we welcome), but one really interesting idea is right there in the abstract:

“We anticipate similar spontaneous knot topology to be a universal feature of waves whose phase front is twisted and nonlinearly modulated, including superfluids and trapped matter waves.” [Emphasis added]

In other words, this research has the potential to be replicated not only to create “knotted waves” of light, but of waves in more tangible stuff.

The superposition Spirograph: different modes of

the knotted soliton. Source: Nature

“Knotted light” is already feature of research into things like optical tweezers and quantum computing. However, according to ANU researcher Dr Anton Desyatnikov, previous demonstrations have been painstakingly hand-made using carefully-engineered lasers.

“[W]hat we’ve been working on are models in which the knots spontaneously form on their own”, he said. “Apart from their curiosity value, what’s really interesting and useful about these knots of darkness is that they show you what the power flow is doing.”

“Our models suggest that you have to get the key parameters of the light in a certain range before you can easily tie the light in knots but once you do, the knots are virtually guaranteed … we can’t predict exactly where they will form. Just that under these specific circumstances the optical vortices will spontaneously nucleate and tie themselves into little knots.” ®

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