There is a shape in physics that is remarkably hard to destroy. You can shake it, heat it, push it and disturb it in every way imaginable, but unless you physically tear the fabric it resides in, it will survive perfectly intact. This is not wishful thinking. It is a mathematical certainty. That shape is called a skyrmion.
The easiest way to picture a skyrmion is to imagine a dartboard covered in tiny arrows. At the very centre, every arrow points straight down into the board. At the outer edge, every arrow points straight up. In between, they rotate smoothly through every possible direction, completing a full rotation and closing back on themselves. This pattern has a score called the skyrmion number, and that score is locked at exactly ±1 (the sign simply defines which way the twist runs). Noise cannot nudge it. Heat cannot drift it. A stray disturbance cannot flip it. The only way to change it is to violently rip the whole pattern apart.
Scientists first found skyrmions hiding inside certain magnetic materials and immediately recognized them as dream candidates for carrying information (a skyrmion present means 1, a skyrmion absent means 0, and nothing in the environment can accidentally corrupt it). But magnetic materials are slow and confined to a chip. The next natural question was bold: what if you could take this indestructible shape and put it inside light itself, travelling freely through open space?
A team of researchers from Tianjin University in China, together with collaborators at Nanyang Technological University in Singapore and Oklahoma State University in the US, has now done exactly that – and gone one step further. As described in Optica, the researchers created not just one skyrmion in light, but two completely different kinds, and found a way to switch between them at will using nothing more than the rotation of a single thin optical half-wave plate.
To read more, click here.