Practical bound for dimensionality in high-dimensional entanglement

Romero, J. and Padgett, M. (2014) Practical bound for dimensionality in high-dimensional entanglement. Proceedings of the National Academy of Sciences of the United States of America, 111(17), pp. 6122-6123. (doi: 10.1073/pnas.1404903111) (PMID:24737892) (PMCID:PMC4035931)

Abstract

The quantum world differs from our classical experience in many ways. Perhaps most curious is the phenomenon of quantum entanglement, where measuring the state of one particle can instantaneously define the state of another, even though the second particle is arbitrarily distant. For much of the 20th century, it was debated whether entanglement really exists. The issue was quantified by Bell’s formulation of the Bell inequality (1), and the subsequent flurry of experiments by Clauser, Aspect, and others, demonstrating that quantum entanglement was real (2⇓–4). All of these early tests were applied to systems where the measured state of one particle can only take one of two values, but such systems are not representative of the wider world. In PNAS, Krenn et al. derive a new entanglement test for systems where the measured state can take on one of many values (Fig. 1) (5). The authors apply their test to the spatial structure (i.e., state) of two separated photons. Krenn et al. confirmed that the photons are entangled over at least 100 of these spatial states. This large number of states allows entanglement in higher dimensions, which can increase both the security of communication and the efficiency of computing protocols (6).

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Padgett, Professor Miles and Romero, Dr Jacqui
• Authors: Romero, J., and Padgett, M.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Proceedings of the National Academy of Sciences of the United States of America
• Publisher: National Academy of Sciences
• ISSN: 0027-8424
• ISSN (Online): 1091-6490