The team devised an experiment to effectively reduce the number of dimensions that the light operates in. First, they passed the light through a crystal, turning the beam into a hollow cylinder with a "screw-like structure." Then, they built a device that measures angular momentum when the light passes through the crystal and also when it bypasses it. In the latter case, the spin was an exact multiple of Planck's constant, as expected, but when it passed through the crystal, the angular momentum shifted by one-half.
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.
The result isn't completely unexpected, as scientists have long theorized that fractional angular momentum in photons is possible in certain instances. However, this is the first time experiments have proved the results -- much like how scientists recently proved that theoretical gravitational waves are a real thing. Practically, engineers could exploit the finding to create faster and more secure forms of data transmission. More importantly, the discovery represents a true breakthrough in quantum mechanics if it stands up. "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," says lead researcher Paul Eastham.