Quantum entanglement is often associated with spin, polarization, or other discrete-valued measurements. But in the 1935 paper in which Albert Einstein, Boris Podolsky, and Nathan Rosen proposed what has come to be known as the EPR paradox, the system they considered involved the entanglement of two continuous-valued quantities, position and momentum. 1 In 1992 researchers from Caltech presented an experimental realization of the EPR paradox for continuous variables. 2 They used beams of light, and the entanglement was displayed in the fluctuations of the optical electric fields.
Now, Vincent Boyer, Alberto Marino, Raphael Pooser, and Paul Lett of the Joint Quantum Institute (JQI; a partnership between the University of Maryland, College Park, and NIST in Gaithersburg, Maryland) have created what they call entangled images, pairs of entangled beams whose cross sections can be represented as assemblages of many independently entangled pixels. 3 And the researchers’ method for producing the beams...
