A particle of light is all you need to create a quantum connection between nearly 3,000 atoms, researchers report in the March 26 Nature. The finding takes physicists a step closer to studying the macroscopic effects of quantum entanglement, which can clarify the properties of microscopic particles. MIT quantum physicist Vladan Vuletić and his coworkers bounced photons between two mirrors in a space that enclosed about 3,100 rubidium atoms cooled to almost absolute zero. Occasionally the polarization of a photon changed marginally, signifying that the photon had interacted with the atoms.
Measurements show that every short-term interaction coaxed at least 2,700 of the atoms to become entangled. The scientists hope to use clusters of entangled atoms to build astonishingly accurate atomic clocks.