Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 25 July 2008:
Vol. 321. no. 5888, pp. 541 - 543
DOI: 10.1126/science.1159663
Prev | Table of Contents | Next

Reports

Entangling the Spatial Properties of Laser Beams

Katherine Wagner,1 Jiri Janousek,1 Vincent Delaubert,1,2 Hongxin Zou,1 Charles Harb,3 Nicolas Treps,2 Jean François Morizur,1,2 Ping Koy Lam,1 Hans A. Bachor1*

Position and momentum were the first pair of conjugate observables explicitly used to illustrate the intricacy of quantum mechanics. We have extended position and momentum entanglement to bright optical beams. Applications in optical metrology and interferometry require the continuous measurement of laser beams, with the accuracy fundamentally limited by the uncertainty principle. Techniques based on spatial entanglement of the beams could overcome this limit, and high-quality entanglement is required. We report a value of 0.51 for inseparability and 0.62 for the Einstein-Podolsky-Rosen criterion, both normalized to a classical limit of 1. These results are a conclusive optical demonstration of macroscopic position and momentum quantum entanglement and also confirm that the resources for spatial multimode protocols are available.

1 Australian Research Council Centre of Excellence for Quantum-Atom Optics, Australian National University, Canberra ACT 0200, Australia.
2 Laboratoire Kastler Brossel, Université Pierre et Marie Curie-Paris 6, ENS, CNRS; 4 place Jussieu, 75252 Paris, France.
3 Australian Defence Force Academy, Canberra, Australia.

* To whom correspondence should be addressed. E-mail: hans.bachor{at}anu.edu.au

Read the Full Text

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)