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

TL;DR

This paper experimentally demonstrates the violation of a Bell inequality in high-dimensional energy-time entangled photons, showing how optimized measurements and state control can reveal quantum nonlocality.

Contribution

It introduces a method to encode and manipulate high-dimensional entangled states in the frequency spectrum of photons using a spatial light modulator, enabling Bell inequality tests in higher dimensions.

Findings

Violation of CGLMP inequality confirmed for 2-qubit and 2-qutrit states.

Controlled generation of maximally and non-maximally entangled qutrits.

Quantum state tomography verified entanglement states.

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.