Scientists find holes in light by tying it in knots


Your daily selection of the latest science news!

According to Phys.org – latest science and technology news stories (This article and its images were originally posted on Phys.org – latest science and technology news stories August 1, 2018 at 11:18AM.)

Scientists find holes in light by tying it in knots

A research collaboration including theoretical physicists from the University of Bristol and Birmingham has found a new way of evaluating how light flows through space—by tying knots in it.

Laser may appear to be a single, tightly focused beam. In fact, it’s an electromagnetic field, vibrating in an ellipse shape at each point in space. This multidirectional light is said to be ‘polarised’.

The effect can be seen with polarised sunglasses, which only allow one direction of light to penetrate. By holding them up to the sky and rotating them, viewers will see darker and brighter patches as light flowing in different directions appears and disappears.

Now, scientists have been able to use holographic technology to twist a polarised laser beam into knots.

Professor Mark Dennis, from the University of Bristol’s School of Physics and University of Birmingham’s School of Physics and Astronomy, led the theoretical part of the research.

He said: “We are all familiar with tying knots in tangible substances such as shoelaces or ribbon. A branch of mathematics called ‘ theory’ can be used to analyse such knots by counting their loops and crossings.

“With light, however, things get a little more complex. It isn’t just a single thread-like beam being knotted, but the whole of the space or ‘field’ in which it moves.

“From a maths point of view, it isn’t the knot that’s interesting, it’s the space around it. The geometric and spatial properties of the field are known as its topology.”

In order to analyse the topology of knotted light fields, researchers from universities in Bristol, Birmingham, Ottowa and Rochester used polarised light beams to create structures known as ‘polarisation singularities’.

Discovered by Professor John Nye in Bristol over 35 years ago, polarisation singularities occur at points where the polarisation ellipse is circular, with other polarisations wrapping around them. In 3 dimensions, these singularities occur along lines, in this case creating knots.

The team were able to create knots of much greater complexity than previously possible in light and analysed them in fine detail.

Professor Dennis added: “One of the purposes of topology is to talk about showing data in terms of lines and surfaces. The real-world surfaces have a lot more holes than the maths predicted.”

Continue reading… | Stay even more current with our live science feed.

  • Got any news, tips or want to contact us directly? Feel free to email us: esistme@gmail.com.

To see more posts like these; please subscribe to our newsletter. By entering a valid email, you’ll receive top trending reports delivered to your inbox.
__

This article and its images were originally posted on [Phys.org – latest science and technology news stories] August 1, 2018 at 11:18AM. All credit to both the author  and Phys.org – latest science and technology news stories | ESIST.T>G>S Recommended Articles Of The Day.

 

 

 

 

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.