The paper “Simple portable quantum key distribution for science outreach” features on the front cover of the first edition of the 2025 American Journal of Physics. The work is authored by Pedro Mendes, a PhD student at Técnico and co-authored by Paulo André and Emmanuel Zambrini Cruzeiro, professors at Técnico and researchers at Instituto de Telecomunicações (IT). The paper presents a simple, compact, and cost-effective setup for undergraduate tutorial demonstrations of Quantum Key Distribution (QKD).
The paper proposes a simplified implementation of QKD, describing all the steps and associated costs, with the aim of providing university professors around the world with a guide on how to set up this experiment for students in a laboratory. The work was carried out at IT’s Quantum Photonics Laboratory (QuLab), which was visited in February by the Greek Deputy Minister for Development.
“QKD is a method for sharing encryption keys using quantum physics”, explains Emmanuel Zambrini Cruzeiro. ‘Any attempt to eavesdrop will alter the key and can be detected, thereby guaranteeing security according to the laws of physics,’ adds the researcher.
In pedagogical terms, the scheme presented in this paper ‘significantly reduces’ the experimental complexity compared to existing literature’. Additionally, the experiment allows for the introduction of several fundamental concepts in quantum physics, such as the generation and detection of coherent states of light.
The American Journal of Physics is a scientific journal that focuses on physics education and teaching, targeting teachers and students who want to clearly understand physics concepts.
