teleportation, in physics, the transfer of key properties from one particle (or group of particles) to another a significant distance apart without a physical connection between the two particles (or groups); also known as quantum teleportation. The two particles involved in the transference are said to be "entangled," that is, the properties of these particles are tied together even when they are far apart. It has been shown that a pair of entangled particles, which were once in contact but later moved too far apart to interact directly, can exhibit individually random behavior that is too strongly correlated to be explained by classical statistics. This phenomenon, called Einstein-Podolsky-Rosen (EPR) correlation or entanglement, was postulated by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935. Physicists once believed teleportation was impossible because it was thought to violate the uncertainty principle of quantum mechanics. However, teleportation has been demonstrated experimentally in a variety of systems, such as photons and coherent light fields. Because teleportation always destroys the particle whose properties are transferred, it is impossible to produce multiple copies of it in this manner.