Quantum Entanglement in the School Lab

It has been less than 100 years since Albert Einstein, Boris Podolsky, and Nathan Rosen highlighted a problem with the then-nascent field of quantum mechanics in a now-famous paper: This new theory predicted correlations between two quantum systems that persist even when the distance between them is arbitrarily large. Einstein, Podolsky, and Rosen considered such a long-range effect to be incompatible with what were believed to be fundamental assumptions of physical theories and concluded that the quantum mechanical description of reality must be incomplete. Shortly thereafter, Erwin Schrödinger coined the term “entanglement” to describe the state of such correlated quantum systems.

Today we know, however, that the fundamental assumptions made at that time are in fact contradicted by experimental results. While quantum entanglement was crucial in leading to this realization, it also continues to offer great potential in numerous fields of application today. Active research is being conducted on the use of entangled quantum systems in areas such as quantum computing, quantum cryptography, and quantum imaging.

It is therefore not surprising that the Conference of Ministers of Education in Germany has included the “quantum physical worldview with regard to the concepts of reality, locality, causality, and determinism” as mandatory content in the educational standards for the General University Entrance Qualification in physics. The phenomenon of quantum entanglement, as a gateway to this subject matter, is thus also highly relevant for school instruction.

In this project, we develop a school lab designed to provide pupils with an introduction to the essence of quantum entanglement. To this end, experiments with entangled photons are vividly simulated using various model and analog experiments. Furthermore, it will be possible to verify the model considerations using a real experiment. Theoretical physics is also represented: Students will be able to prove the CHSH inequality, a prominent theorem for testing local realism in quantum mechanics.