New Quantum Record: Physicists Entangle 8 Photons
One of the most mind-blowing areas of quantum mechanics is entanglement: two or more particles separated in space can have physical properties that are correlated. A measurement performed on one particle will tell us the result of the same measurement taken on an entangled particle. Entanglement is important but difficult to study, both in terms of a theoretical understanding and doing experiments. While entangling relatively small groups of particles has been accomplished several times over the last 30 years, scaling these experiments up in sizes sufficient to create quantum computers and other complex systems has eluded researchers.
A significant step forward has been accomplished by entangling eight photons (previously six had been the largest number). Researchers from Shanghai’s University of Science and Technology of China created a system where eight photons were equally likely to be polarized in a specific orientation, something known colloquially as a “Schrödinger cat” state. In a paper published in Nature Photonics, authors Xing-Can Yao et al. describe a new technique that uses ultra-bright photon sources to control for some of the problems that plagued earlier entanglement experiments.