2007/08/31 by Tomohisa Nagata, Ryo Okamoto, Jeremy L. O'Brien +2 · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1126/science.1138007
published as Science 316, 726-729 (2007) · 5 pages, 4 figures Author name was slightly modified
arxiv created 2007/10/22 · arxiv updated 2009/12/01
Precision measurements are important across all fields of science. In particular, optical phase measurements can be used to measure distance, position, displacement, acceleration and optical path length. Quantum entanglement enables higher precision than would otherwise be possible. We demonstrate an optical phase measurement with an entangled four photon interference visibility greater than the threshold to beat the standard quantum limit--the limit attainable without entanglement. These results open the way for new high-precision measurement applications.