World Quantum Day 2025: Return of the QuanTour Light Source, Hands-on Experiments, and an Enjoyable Science Slam

Quantum technology took the stage in Berlin on April 14. The highlight was the ceremonial return of the QuanTour light source to Urania, – a symbolic conclusion to a year-long journey through European research institutions. The QuanTour linked laboratories and universities across Europe as a precursor to this year’s International Year of Quantum Science and Technology.

“With the QuanTour, we wanted to set an example for networking, transparency and enthusiasm for quantum technology,” say the initiators, Doris Reiter and Tobias Heindel, who had the idea for the project two years ago. “Due to the great interest, the QuanTour light source will make one more stop in Turkey before being passed on to the Physikalisch-Technische-Bundesanstalt.”

Measuring the same quantum light source more than a dozen times in different laboratories is a unique experiment and an important step toward establishing standards for quantum technologies. At the same time, the QuanTour made quantum research visible to the public across Europe: researchers gave insights into the physics laboratories and their everyday life in science via Instagram and in a podcast.

In addition to the return of the light source, the World Quantum Day event offered a varied program with numerous interactive experiments, workshops, and a hands-on exhibition. During the workshop on quantum cryptography, students could playfully try out for themselves how a secret key is transmitted in the form of a random bit sequence using individual photons, and whether this was intercepted. Another workshop illustrated quantized conductance. With experimental skill, participants were able to observe quantum jumps in the conductance of gold wire using an oscilloscope by carefully pulling two gold wires apart.

In the hands-on exhibition, quantum phenomena such as superposition and entanglement were made accessible in a playful way, for example with the game Quantum Tic-Tac-Toe by the Junge Tüftler:innen or the artwork Quantum Jungle, which visualized the Schrödinger equation. The analogue Paul Trap by Q-Bus demanded skill in handling an ion trap experiment made of wood. The program was complemented by the touring exhibition Rethinking Physics, which highlighted the role of women in science. The booths of Leap, AQLS, Berlin Partner, BTU, and The Science Talk provided information about the multifaceted quantum landscape in Berlin.

The highlight of the evening was a Quantum Science Slam: five young researchers presented their scientific work in a creative and easy-to-understand way, from molecular films and stardust quantum computers to motion-dependent quantum emotions. Science journalist and physicist Sabrina Patsch, who humorously explained quantum entanglement using the fictional animals Quaninchen and Queerschweinchen, won the slam.

Cover picture © DPG / Mauro Franceschetti