In the Quantum Memory Laboratory at the University of Warsaw, the group of three physicists was the first to create such an entangled state, which consisted of a macroscopic object—a group of about one trillion atoms, and a single photon. "Single photons, scattered during the interaction of a laser beam with atoms, are registered on a sensitive camera. A single registered photon carries information about the quantum state of the entire group of atoms. The atoms may be stored, and their state may be retrieved on demand," says Michal Dabrowski, Ph.D. student and co-author of the article.
The results of the experiment confirm that the atoms and the single photon are in a joint entangled state. By measuring the position and momentum of the photon, the researchers acquired all information about the state of atoms. To confirm this, polish scientists converted the atomic state into another photon, which was measured using the same state-of-the-art camera.
Read more at: https://phys.org/news/2017-03-quantum-entanglement-photon-trillion-rubidium.html#jCp