One property of quantum physics that has long stumped philosophers and physicists is entanglement, which refers to the process whereby entangled quanta of light exert influences on each other no matter how much distance is between them. Now, researchers from the University of Vienna have entangled three particles of light by "twisting" them together using their wavefront structure.
In order to grasp entanglement, think of two ice dancers - imagine that when one twirls counterclockwise, the other does the same, even if they are located on two different continents.
"The entangled photons in our experiment can be illustrated by not two, but three such ice dancers, dancing a perfectly synchronized quantum mechanical ballet," Mehul Malik, first author of the paper, said in a press release. "Their dance is also a bit more complex, with two of the dancers performing yet another correlated movement in addition to pirouetting. This type of asymmetric quantum entanglement has been predicted before on paper, but we are the first to actually create it in the lab."
In order to create the unique twisted photon state, the team combined two pairs of high-dimensionally entangled photons in a way that made it impossible to determine where a particular photon originated, effectively creating a quantum protocol that allows various layers of information to be shared among multiple parties with complete security.
"The experiment opens the door for a future quantum Internet with more than two partners and it allows them to communicate more than one bit per photon," said Anton Zeilinger, who participated in the research.
Future studies will need to be conducted before a quantum communication protocol is possible, although the rapid pace of quantum technology progression likely means that these studies are not too far off.
The findings were published in the Feb. 29 issue of Nature Photonics.
