Another way to characterize twisted light for quantum communications
There is also no known fundamental limit to the maximum OAM value that can be coded into a photon, which could allow for quicker communication than with other systems.
To this end, researchers at the University of Rochester have overcome experimental challenges to demonstrate a new way for getting a full picture of twisted light: characterizing the Wigner distribution.
But before any particular system can be used in quantum communication, researchers need to be able to measure it and describe it. Other methods to obtain the wavefunction, a property that describes a quantum system in full – such as quantum tomography or direct measurements – have been demonstrated in the past. However, in a Physical Review Letters paper published this week, the Rochester researchers state that their technique is particularly “suitable for quantum information applications involving a large number of OAM states.”
The Wigner distribution is a mathematical construct that completely describes a system in terms of two conjugate variables, that is two variables linked by Heisenberg’s Uncertainty Principle. Mohammad Mirhosseini, a postdoctoral associate in Professor of Optics Robert W. Boyd’s group, and his collaborators at the Institute of Optics have now shown how the Wigner distribution can be obtained for twisted light. The work also represents the first characterization of the Wigner distribution that involves a discrete variable, as is the case with OAM.
“Apart from the potential uses in quantum communication, our work might offer a good way for describing atomic systems with quantized levels,” said Mirhosseini. “The Wigner distribution of twisted light is a very complete way to understand the system: not only does it tell us about the relation between these two linked variables, but it also tells us about the system’s behavior. We showed that the Wigner distribution for twisted light superpositions contains negative values, which reveals wave-like behavior.”