Innovative approaches of teaching quantum physics based on experiments is the main focus of our research group. This web page provides interactive representations of the experiments in our laboratory. We can demonstrate fundamental phenomena of quantum physics such as quantum particles, randomness and entanglement as well as prospective applications like quantum random number generation and quantum cryptography. Our target group are students of physics in secondary schools, colleges and universities, and their teachers. The web page will be supplemented frequently.
Photon – an examplary quantum object
Foundations of quantum physics can be demonstrated with different types of microscopic objects, such as electrons, neutrons, atoms, molecules and Bose-Einstein-condensates. We have chosen photons, because they are easy to handle. In the field of experimental quantum physics, many effects are first shown with photons and then extended to more advanced techniques. Photon based systems for quantum cryptography are now commercially available [IdQ08].
Demonstration experiments in physics education
Photons have been discussed in virtually every curriculum of quantum physics for a long time. Canonical demonstration experiments such as the photoelectric effect [Mil16] and Compton-effect [Com22] are shown for their importance in the development of nonrelativistic quantum physics. However, after completion of the theory, it was discovered that these ground-breaking experiments can perfectly be explained with a model of quantized atoms interacting with a classical electromagnetic wave [Man64], [Lam69]. Only recently, experiments on the quantum nature of light have been introduced to physics education [Tho04], [Gal05]. Today, there still is a high potential to include non-classical behaviour of light, i.e. non-trivial properties of the photon, into physics curricula ranging from advanced high school to undergraduate university level.
We would like to extend the range of quantum optics experiments for educational purposes and eventually develop a curriculum based on experimental observation rather than historic development or formal structures. Applications of modern quantum optics such as quantum cryptography are included for motivation. Students gain insight to methods and equipment of modern research laboratories at an early stage of education. Our laboratory will be used by students of the Friedrich Alexander University in Erlangen / Germany and local high schools. For preparing a visit, we provide interactive screen experiments. We hope that these screen experiments are also useful for interested students who live too far away for a visit.
The experiments with single photons normally need complete darkness. We use narrow bandpassfilters (810±10nm) in front of every detector. With the filters we can illuminate our laboratory with white LED lamps (<750nm) and work in a bright laboratory while measurements are made.
Interactive screen experiments
Interactive screen experiments or ISE [Kir07] are based on a large set of photographs of an experiment in different configurations. The user can interactively change the setting of a component and will see how the experiment reacts. Due to the relative complexity of our experiments compared to earlier ISE, we had to limit the number of interactive components. Typically, one can alter the settings of components critical to the experiment, while the optical alignment remains fixed. The data shown in the interactive experiments are not calculated! They are generated with the setup under the conditions available to the user, and stored on the server. All data include measurement errors, which are not filtered out.
Author: P. Bronner, 2008