Random Accesses

Scientists at the California Institute of Technology (Caltech) have developed an efficient method to detect entanglement shared among multiple parts of an optical system. They show how entanglement, in the form of beams of light simultaneously propagating along four distinct paths, can be detected with a surprisingly small number of measurements. Entanglement is an essential resource in quantum information science, which is the study of advanced computation and communication based on the laws of quantum mechanics.

In the May 8 issue of the journal Science, H. Jeff Kimble, the William L. Valentine Professor and professor of physics at Caltech, and his colleagues demonstrate for the first time that quantum uncertainty relations can be used to identify entangled states of light that are only available in the realm of quantum mechanics. Their approach builds on the famous Heisenberg uncertainty principle, which places a limit on the precision with which the momentum and position of a particle can be known simultaneously.

Entanglement, which lies at the heart of quantum physics, is a state in which the parts of a composite system are more strongly correlated than is possible for any classical counterparts, regardless of the distances separating them.

Source: http://www.eurekalert.org/pub_releases/2009-05/ciot-cpd050809.php