Skip to main content
Physicists just discovered a totally new form of light



Science, always keeping us on our toes.
Physicists have just discovered a new form of light that doesn't follow our existing rules of angular momentum, and it could shake up our understanding of the electromagnetic radiation and lead to faster, more secure optical communication.
Because of how well-studied and, well, everywhere, light is, you might assume that we've pretty much learnt all there is to know about it. But just last year, researchers identified a fundamental new property of light, and now a team of Irish scientists has shown that light can take on unexpected new forms.
One of the ways we measure a beam of light is through its angular momentum - a constant quantity that measures how much light is rotating. And until now, it was thought that for all forms of light, the angular momentum would be a whole number (known as an integer) multiple of Planck's constant - a physical constant that sets the scale of quantum effects.
But researchers led by Trinity College Dublin have now demonstrated that a new form of light exists, where the angular momentum is only half of this value.
"What I think is so exciting about this result is that even this fundamental property of light, that physicists have always thought was fixed, can be changed," said lead researcher Paul Eastham.
Let's back up for a second here and explain what all that means.
As one of the researchers, Kyle Ballantine, explains:
"A beam of light is characterised by its colour or wavelength and a less familiar quantity known as angular momentum. Angular momentum measures how much something is rotating. For a beam of light, although travelling in a straight line, it can also be rotating around its own axis. So when light from the mirror hits your eye in the morning, every photon twists your eye a little, one way or another."
As mind-bending as that might sound, it's all well understood by physicists. But what they didn't realise was that light could exist that had an angular momentum that wasn't a whole number.
To figure this out, the team passed light through crystals to create beams of light that had a twisted, screw-like structure. They were looking for new light behaviours that might improve optical communications, but when they analysed this particular beam within the theory of quantum mechanics, it looked as though its angular moment would be a half-number - which definitely wasn't what they'd expected to find. 
They then came up with an experiment to test this prediction, and were able to construct a device that measured the flow of angular momentum within the light beam, as well as the variation in this flow caused by quantum effects.
Usually any of those quantum variations would cause the angular moment to change by whole numbers, based on our understanding of physics so far. But the experiments revealed a tiny shift - one-half of Planck's constant - in the angular momentum of each photon. 
That's really exciting, not only because it's a brand new form of light, but because since the 1980s, theoretical physics have predicted that quantum mechanics would enable the possibility of particles whose quantum numbers were fractions of those expected. And now, for the first time, this work proves those predictions right, using one our best-studied particles.
"The topic of light has always been one of interest to physicists, while also being documented as one of the areas of physics that is best understood," said one of the researchers, Stefano Sanvito. "This discovery is a breakthrough for the world of physics and science alike."
The biggest impact, other than shaking up our understanding of light, is that this new information could help to improve speed and security along fibre-optic cables, leading to faster, safer internet connections.
But before we get anywhere close to benefitting from this new form of light, another team of researchers will need to replicate and validate this work to make sure it wasn't just a one-off. Science is often a slow process, but there's no denying its an exciting one.
And if you're still stuck trying to figure out exactly what angular momentum actually is, don't worry, we've all been there:



Comments

Popular posts from this blog

This strange mineral grows on dead bodies and turns them blue

If you were to get up close and personal with Ötzi the Iceman – the 5,000-year-old mummy of a  tattooed ,  deep-voiced  man who died and was frozen in the Alps – you’d notice that his skin is flecked with tiny bits of blue. At first, it would appear that these oddly bluish crystal formations embedded in his skin are from freezing to death or some other sort of trauma, but it’s actually a mineral called  vivianite  (or blue ironstone) and it happens to form quite often on corpses left in iron-rich environments. For Ötzi, the patches of vivianite are  from him resting  near rocks with flecks of iron in them, but other cases are way more severe. According to Chris Drudge at Atlas Obscura , a man named John White was buried in a cast iron coffin back in 1861. During those days, coffins often had a window for grieving family members to peer inside even if the lid was closed during the funeral. Sometime after he was buried, that window broke, allowing groundwater to come inside the

It's Official: Time Crystals Are a New State of Matter, and Now We Can Create Them

Peer-review has spoken. Earlier this year , physicists had put together a blueprint for how to make and measure time crystals - a bizarre state of matter with an atomic structure that repeats not just in space, but in time, allowing them to maintain constant oscillation without energy. Two separate research teams managed to create what looked an awful lot like time crystals  back in January,  and now both experiments have successfully passed peer-review for the first time, putting the 'impossible' phenomenon squarely in the realm of reality. "We've taken these theoretical ideas that we've been poking around for the last couple of years and actually built it in the laboratory,"  says one of the researchers , Andrew Potter from Texas University at Austin. "Hopefully, this is just the first example of these, with many more to come." Time crystals  are one of the coolest things physics has dished up in recent months, because they point to a

The Dark Side Of The Love Hormone Oxytocin

New research shows oxytocin isn't the anti-anxiety drug we thought it was. Oxytocin, the feel-good bonding hormone released by physical contact with another person, orgasm and childbirth (potentially encouraging  monogamy ), might have a darker side. The  love drug  also plays an important role in intensifying  negative emotional memories  and increasing feelings of fear in future stressful situations, according to a new study. Two experiments performed with mice found that the hormone activates a signaling molecule called extracellular-signal-related kinases (ERK), which has been associated with the way the brain  forms memories   of fear . According to Jelena Radulovic, senior author on the study and a professor at Northwestern University's medical school, ERK stimulates fear pathways in the brain's lateral septum, the region with the highest levels of oxytocin. Mice without oxytocin receptors and mice with even more oxytocin receptors than usual were placed in