Researchers from the Department of Fundamental Problems of Technology have just taken over an unusual briefcase that has arrived following a series of visits to laboratories in much of Europe. The briefcase contains a source of single photons with a quantum dot active region, which will undergo a series of tests here and become an opportunity to demonstrate how much potential this speck of crystal has and why research into it is being carried out by so many teams at our university and in other parts of the world.

The globe-trotting dot embarked on its tour of Europe last year, in Berlin. The tour of 12 countries on our continent is part of the celebration of the 100th anniversary of quantum physics, falling in 2025, which was jointly announced by UNESCO and the United Nations General Assembly. The tour of European research laboratories has become known as the QuanTour and is an initiative of the German Physical Society.

“It's all about popularising quantum technologies and the knowledge of quantum dots themselves, as well as giving us scientists working with quantum dots the opportunity to bond and learn more about the details of our research,” says Anna Musiał, PhD, Eng. from the Laboratory of Optical Nanostructure Spectroscopy at the Department of Experimental Physics, who coordinates the Polish part of the quantum dot journey.

So far, the briefcase containing the dot has visited Germany, Austria, Italy, Switzerland, Spain, France, the UK, Ireland, Scotland, the Netherlands, Denmark, and Sweden. It will return home to Germany when its stay in Poland is over. In our country, it has already spent some time at the laboratories of Adam Mickiewicz University in Poznań and now has arrived at our university. We will then transfer it to the Military University of Technology and on to the University of Warsaw.

“At every European university that it has been to, identical research into it is carried out,” says Dr Anna Musiał. “We check that its emission is unchanged, i.e. that nothing has happened to it despite the passage of time, changing conditions, and the hardships of the journey. We also investigate the impact of the optical cavity in which the dot is placed. The final part of the research consists in analysing whether the photons that the dot emits are actually emitted singly, which is relevant to the potential use of such dots in quantum cryptography.

Dr Musiał emphasises that the demonstration of these elements will help prove that the quantum dot can be seen as a stable emitter of single photons.

What could we use quantum dots for in the future? Read our article.

In addition, the dot will also undergo structural studies at Wrocław Tech, i.e. analysis of the optical cavity structure under an atomic force microscope. This will allow the quality and cleanliness of the surface of the structure to be investigated after such a long journey and confirm the dimensions of the optical cavity in which the quantum dot is placed. This will be handled by scientists from the Nanoscale Observation and Manipulation Laboratory, led by Prof. Teodor Gotszalk at the Faculty of Electronics, Photonics and Microsystems.

Popular science events are also being organised at each site in the quantum dot’s itinerary, and it will be no different at our university. The quantum dot with its peculiarities and potential applications will be presented to over 200 secondary school students who will attend Quantum Dot Day, i.e. on Tuesday, 11 March, and to all interested parties who will attend our open-door afternoon event on the same day.

The QuanTour can also be followed on a dedicated official Instagram profile and on the project's website, which also features trivia related to quantum physics and video interviews with researchers from the various research centres visited by the dot.

lucy