Full-Field Quantum Correlations of Spatially Entangled Photons

Abstract

Spatially entangled twin photons allow the study of high-dimensional entanglement, and the Laguerre-Gauss modes are the most commonly used basis to discretize the single-photon mode spaces. In this basis, to date only the azimuthal degree of freedom has been investigated experimentally due to its fundamental and experimental simplicity. We show that the full spatial entanglement is indeed accessible experimentally; i.e., we have found practicable radial detection modes with negligible cross correlations. This allows us to demonstrate hybrid azimuthal-radial quantum correlations in a Hilbert space with more than 100 dimensions per photon.

Two-photon optics of Bessel-Gaussian modes

“…Depending on the azimuthal index an incoming Gaussian mode is transformed into an approximated LG mode carrying the OAM of h per photon. This is only an approximation, as the radial dependence of 033818-3 the LG function has been neglected in favor of efficiency [11,12]. By selecting the BG basis in which to measure OAM entanglement, we have access to a continuous scaling parameter for the radial component of the BG modes.…”

“…Without this approximation, the LG modes are still close to being the Schmidt basis [10,11]. Thus, the LG modes are entangled not * aforbes1@csir.co.za only in the azimuthal index, but also in terms of the radial index [12]. High-dimensional entanglement is dependent on the number of usable OAM modes in the state [13].…”

Quantum-secure authentication of a physical unclonable key

“…Details are provided in Supplement 1. The challenges are high-spatial-dimension states of light [9][10][11] with only a few photons. The response is speckle-like and depends strongly on the challenge and the positions of the scatterers.…”

Observation of Four-Photon Orbital Angular Momentum Entanglement

“…This enables implementation of novel quantum information protocols [3][4][5], and the study of fundamentally new quantum states [6,7]. To date, only two such multidimensional particles have been entangled [8,9] albeit with ever increasing dimensionality [10][11][12]; only in continuous variables, a first study goes beyond this [13]. Here, we use pulsed spontaneous parametric downconversion (SPDC) [14] to produce photon quadruplets that are entangled in their OAM, or transverse-mode, degrees of freedom [8,15], and witness genuine multipartite Dicke-type entanglement [16][17][18].…”