Southwest Quantum Information and Technology

Q-plates for entangling photon spin and orbital angular momentum

Presenting Author: Hannah Knaack, Harvey Mudd College
Contributing Author(s): Morgan Mastrovich and Theresa W. Lynn

Photon polarization is a popular qubit variable, partially because it is so accessible, while orbital angular momentum is more difficult to manipulate and measure. However, the dimensionality of orbital angular momentum as a qudit is limited only by our technical ability to create and manipulate it. Q-plates shift orbital angular momentum in photons based on their incoming polarization, enabling the creation of entangled qubit-qudit systems on a single particle. A q-plate consists of a liquid crystal half-wave plates with a spatially varying axis. The “q” of the plate is defined by the number of complete revolutions the axis makes around the plate, and determines the magnitude of the angular momentum imparted. We are working to fabricate q-plates for use in quantum communications applications. We plan to create entanglement between the spin and orbital angular momentum degrees of freedom of a single photon, then to create multipartite entanglement on a photon pair produced by spontaneous parametric down-conversion.

(Session 5 : Thursday from 5:00pm - 7:00pm)