Satisfying the Einstein-Podolsky-Rosen criterion with massive particles
Authors: Peise J., Kruse I., Lange K., Lucke B., Pezzè L., Arlt J., Ertmer W., Hammerer K., Santos L., Smerzi A., Klempt C.
Autors Affiliation: Leibniz Univ Hannover, Inst Quantenopt, Welfengarten 1, D-30167 Hannover, Germany; INO CNR, QSTAR, Largo Enrico Fermi 2, I-50125 Florence, Italy; LENS, Largo Enrico Fermi 2, I-50125 Florence, Italy; Aarhus Univ, Inst Fysik & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark; Leibniz Univ Hannover, Inst Theoret Phys, Appelstr 2, D-30167 Hannover, Germany
Abstract: 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, as shown successfully with light fields. Here, we report on the production of massive particles which meet the EPR criterion for continuous phase/amplitude variables. The created quantum state of ultracold atoms shows an EPR parameter of 0.18(3), which is 2.4 standard deviations below the threshold of 1/4. Our state presents a resource for tests of quantum nonlocality with massive particles and a wide variety of applications in the field of continuous-variable quantum information and metrology.
KeyWords: Bose-Einstein condensate; Einstein-Podolsky-Rosen entanglement; atomic homodyning