Twist a two-dimensional strip of paper then tape its ends together and it transforms into a one-sided loop. It鈥檚 not magic; it鈥檚 a M枚bius strip. These mathematical structures show up everywhere from to , but almost never in nature. Now, a team of physicists have shown for the first time that light can be coaxed into a M枚bius shape.

鈥淟ight can kind of turn one-sided and single-edged under certain conditions,鈥� says of the Max Planck Institute for the Science of Light in Erlangen, Germany.

Banzer and his colleagues were following up on predictions made by at Bar-Ilan University in Israel, who first suggested in 2005 that light鈥檚 polarisation, a property that describes how its electric field moves, . If proved experimentally, the phenomenon could pave the way for fundamental studies of how light and matter interact, such as using light to trap tiny particles for biomedical purposes.

Let鈥檚 twist again

In 2010, Freund : prepare two polarised beams of light and allow them to interfere with each other in a particular way. The interference will cause the polarisation to twist, forming a M枚bius strip.

Banzer鈥檚 team scattered two polarised green laser beams off a gold bead that was smaller than the wavelength of the light. The resulting inference introduced a polarisation pattern with either three or five twists, giving it a M枚bius-like structure.

鈥淭hese results are the first (experimental) proof that polarisation M枚bius strips really exist, which has been a decade-long question in the community,鈥� Banzer says. 鈥淭hese findings emphasise the richness of light and its properties.鈥�

鈥淭he study is a brilliant tour de force at the cutting edge of optical technology,鈥� says Freund. 鈥淭he real significance of this study goes far beyond verifying a particular prediction, because it demonstrates that it is possible to measure the full three-dimensional polarisation structure of light.鈥�

Journal reference: Science, DOI: