Undergraduate setup for measuring the Bell inequalities and performing Quantum State Tomography

TL;DR

This paper introduces an accessible, cost-effective experimental setup for students to measure Bell inequalities and perform quantum state tomography on entangled photons, enhancing quantum physics education.

Contribution

The paper presents a versatile, affordable photon system with two variants enabling Bell tests and quantum state tomography suitable for classroom use.

Findings

Successful generation of high-fidelity entangled states

Significant violations of Bell's inequalities achieved

Setup demonstrated effective manipulation of quantum states

Abstract

The growth of quantum technologies is attracting the interest of many students eager to learn concepts such as quantum entanglement or quantum superposition. However, the non-intuitive nature of these concepts poses a challenge to understanding them. Here, we present an entangled photon system which can perform a Bell test, i.e. the CHSH inequality, and can obtain the complete tomography of the two-photon state. The proposed setup is versatile, cost-effective and allows for multiple classroom operating modes. We present two variants, both facilitating the measurement of Bell inequalities and quantum state tomography. Experimental results showcase successful manipulation of the quantum state of the photons, achieving high-fidelity entangled states and significant violations of Bell's inequalities. Our setup's simplicity and affordability enhances accessibility for less specialized laboratories, allowing students to familiarize themselves with quantum physics concepts.