Amplitude damping channel for orbital angular momentum

Abstract

Since the pioneering work on the entanglement of the orbital angular momentum (OAM) states of light, much attention has been devoted to the subject, with particular attention into the quantum aspects of information processing using OAM. Furthermore it has recently been shown that the time evolution of the entanglement of a qubit pair caused by a quantum channel acting on one of the qubits can be determined for any initial state by probing only the entanglement evolution of the maximally entangled state. This is most beneficial in experimentally characterizing the entanglement dynamics of unknown channels. In this paper the authors outline a simple experiment to test this prediction using the OAM states of light; their approach is an extension of a previously reported OAM sorting device. A Mech-Zehnder interferometer with a Dove prism in each arm is used to sort OAM states according to their parity. The authors extend this concept to implement an amplitude damping channel, and prove its action on the OAM states both theoretically and experimentally.