A research group from the University of Gdańsk's Institute of Theoretical Physics and Astrophysics, in collaboration with scientists from LMU Munich and MTA Debrecen, has published an article entitled Unmasking the Polygamous Nature of Quantum Nonlocality in the prestigious journal Proceedings of the National Academy of Sciences (USA).
The article describes the latest research into quantum entanglement - a phenomenon that occurs in the microworld and has no equivalent in our everyday experience.
‘Quantum particles, even at any distance, can be linked to each other in ways that are stronger and less obvious than their classical counterparts. These links manifest themselves in experiments as correlations between the results of measurements on separated particles,’ says PhD student Pawel Cieśliński.
Such correlations cannot be described by the laws of classical physics. This effect was called nonlocality, and its experimental verification was honoured with the Nobel Prize in Physics in 2022. Until now, the prevailing view among physicists has been that there are strong constraints on the sharing of nonlocality in systems of many particles. In the simplest case, where three particles are studied, only one of the three possible pairs can have this property. This phenomenon has been called ‘monogamy of nonlocality’.
‘Our latest research has shown that the principle of monogamy does not apply universally. When we extend the system to a larger number of particles, nonlocality can manifest itself not only between many, but even between all particles at the same time, which we have described as polygamy,' said prof. dr hab. Wieslaw Laskowski, Vice-Rector for Research.
Theoretical predictions have been confirmed experimentally in systems of entangled photons thanks to cooperation with the group of Prof. Harald Weinfurter (Ludwig and Maximilian University of Munich). The results provide a better understanding of the fundamental nature of the world around us and have promising applications in modern quantum technologies, including quantum cryptography, quantum device testing and communication complexity reduction.
‘UG students were also involved in the work. This is already the third generation of quantum physicists from the University of Gdańsk who are successfully researching issues of quantum nonlocality,’ adds prof. dr hab. Tomasz Paterek.
The team from the University of Gdańsk consists of Prof. Wiesław Laskowski, PhD, Prof. Tomasz Paterek, doctoral student Paweł Cieśliński and student Mateusz Kowalczyk. The paper was written in collaboration with prof. Harald Weinfurter as well as dr Lukas Knips (LMU Munich) and dr Tamás Vértesi (MTA Debrecen - Hungarian Academy of Sciences).
The work of the Gdańsk researchers was funded by the National Science Centre.