2001/06/30 by Brian Julsgaard, Alexander Kozhekin, Eugene S. Polzik · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1038/35096524
Submitted to Nature, June 9, 2001, 11 pages, 3 figures. Contents changed following referees' suggestions
arxiv created 2001/07/19 · arxiv updated 2009/12/01
Entanglement is considered to be one of the most profound features of quantum mechanics. An entangled state of a system consisting of two subsystems cannot be described as a product of the quantum states of the two subsystems. In this sense the entangled system is considered inseparable and nonlocal. It is generally believed that entanglement manifests itself mostly in systems consisting of a small number of microscopic particles. Here we demonstrate experimentally the entanglement of two objects, each consisting of about 1012 atoms. Entanglement is generated via interaction of the two objects - more precisely, two gas samples of cesium atoms - with a pulse of light, which performs a non-local Bell measurement on collective spins of the samples. The entangled spin state can be maintained for 0.5 millisecond. Besides being of fundamental interest, the robust, long-lived entanglement of material objects demonstrated here is expected to be useful in quantum information processing, including teleportation of quantum states of matter and quantum memory.