Satisfying the Einstein-Podolsky-Rosen criterion with massive particles

Understand

In 1935, Einstein, Podolsky and Rosen (EPR) questioned the completeness of quantum mechanics by devising a quantum state of two massive particles with maximally correlated space and momentum coordinates.

• The EPR criterion qualifies such continuous-variable entangled states, where a measurement of one subsystem seemingly allows for a prediction of the second subsystem beyond the Heisenberg uncertainty relation.
• Up to now, continuous-variable EPR correlations have only been created with photons, while the demonstration of such strongly correlated states with massive particles is still outstanding.
• Here, we report on the creation of an EPR-correlated two-mode squeezed state in an ultracold atomic ensemble.