Experimental violation of a d-dimensional Bell inequality using energy-time entangled photons

Abstract

We experimentally study the violation of the CGLMP inequality for entangled 2-qubit and 2-qutrit states with different degrees of entanglement using numerically optimized measurement settings. The qudits are encoded and manipulated in the frequency spectrum of broadband energy-time entangled photons by taking into account a spatial light modulator. The latter allows to discretize the spectrum into bins. By controlling each frequency bin individually, the generation of maximally and non-maximally entangled qutrits is verified through quantum state tomography.

High‐Dimensional Quantum Communication: Benefits, Progress, and Future Challenges

“…Thus, it is possible to identify noise thresholds, for each dimension d , such that if exceeded the quantum‐to‐classical transition will emerge, making large systems behaving classically under Bell‐like tests. Experimental violation of generalized Bell inequalities have been achieved with energy–time entangled qutrits ( qudit), with entangled radial and angular degrees of freedom of Laguerre–Gauss (LG) modes for qudits with dimension and up to with entangled qudits encoded in the OAM degree of freedom . The larger violation of Bell inequalities gives also benefit on entanglement‐based device‐independent QKD protocols.…”

Bipartite Bell inequalities with three ternary-outcome measurements—from theory to experiments

“…As depicted in figure 1, our experimental setup [86,87] can be subdivided into three parts: preparation, manip- n , whereas the second column gives the local bound S L max , i.e., the maximum value of the Bell expression allowed by all P ∈ L, cf. Eq.…”

Entangled Photon-Pair Sources based on three-wave mixing in bulk crystals

“…The reduction in coincidence detection due to post-selection is eliminated by the use polarization entangled photon source with Type-II crystal [5] to demonstrate energy-time entanglement [205]. Energy-time entangled states in high dimensions were also demonstrated with continuous-wave SPDC sources [206][207][208][209] and discretization of frequency spectrum using spatial light modulators for labelling qudits [210]. It was proposed that the use of multiple Franson interferometers in Alice and Bob increases the sensitivity against certain photon localization attacks in high dimensional energy-time entanglement based quantum key distribution systems [211].…”