Experimental generation and characterization of single-photon hybrid ququarts based on polarization-orbital angular momentum encoding

TL;DR

This paper demonstrates the experimental creation and measurement of four-dimensional quantum states, or ququarts, encoded in a single photon's polarization and orbital angular momentum, using a novel q-plate based technique.

Contribution

It introduces a new method for generating and measuring high-dimensional quantum states with a q-plate device, enabling full state tomography in all mutually unbiased bases.

Findings

Successful generation of ququarts in all five mutually unbiased bases

Reconstruction of the four-dimensional density matrix for various states

Validation of the q-plate technique for high-dimensional quantum state control

Abstract

High-dimensional quantum states, or qudits, represent a promising resource in the quantum information field. Here we present the experimental generation of four-dimensional quantum states, or ququarts, encoded in the polarization and orbital angular momentum of a single photon. Our novel technique, based on the q-plate device, allows to prepare and measure the ququart in all five mutually unbiased bases. We report the reconstruction of the four dimensional density matrix through the tomographic procedure for different ququart states.