TY - JOUR A1 - Mari, Andrea A1 - Kieling, Konrad A1 - Nielsen, B. Melholt A1 - Polzik, E. S. A1 - Eisert, Jens T1 - Directly estimating nonclassicality JF - Physical review letters N2 - We establish a method of directly measuring and estimating nonclassicality-operationally defined in terms of the distinguishability of a given state from one with a positive Wigner function. It allows us to certify nonclassicality, based on possibly much fewer measurement settings than necessary for obtaining complete tomographic knowledge, and is at the same time equipped with a full certificate. We find that even from measuring two conjugate variables alone, one may infer the nonclassicality of quantum mechanical modes. This method also provides a practical tool to eventually certify such features in mechanical degrees of freedom in opto-mechanics. The proof of the result is based on Bochner's theorem characterizing classical and quantum characteristic functions and on semidefinite programming. In this joint theoretical-experimental work we present data from experimental optical Fock state preparation. Y1 - 2011 U6 - https://doi.org/10.1103/PhysRevLett.106.010403 SN - 0031-9007 VL - 106 IS - 1 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Zoller, Peter A1 - Beth, Thomas A1 - Binosi, D. A1 - Blatt, Rainer A1 - Briegel, Hans J. A1 - Bruss, D. A1 - Calarco, Tommaso A1 - Cirac, Juan Ignacio A1 - Deutsch, David A1 - Eisert, Jens A1 - Ekert, Artur A1 - Fabre, Claude A1 - Gisin, Nicolas A1 - Grangiere, P. A1 - Grassl, Markus A1 - Haroche, Serge A1 - Imamoglu, Atac A1 - Karlson, A. A1 - Kempe, Julia A1 - Kouwenhoven, Leo P. A1 - Kröll, S. A1 - Leuchs, Gerd A1 - Lewenstein, Maciej A1 - Loss, Daniel A1 - Lütkenhaus, Norbert A1 - Massar, Serge A1 - Mooij, J. E. A1 - Plenio, Martin Bodo A1 - Polzik, Eugene A1 - Popescu, Sandu A1 - Rempe, Gerhard A1 - Sergienko, Alexander A1 - Suter, David A1 - Twamley, John A1 - Wendin, Göran A1 - Werner, Reinhard F. A1 - Winter, Andreas A1 - Wrachtrup, Jörg A1 - Zeilinger, Anton T1 - Quantum information processing and communication : Strategic report on current status, visions and goals for research in Europe N2 - We present an excerpt of the document "Quantum Information Processing and Communication: Strategic report on current status, visions and goals for research in Europe", which has been recently published in electronic form at the website of FET (the Future and Emerging Technologies Unit of the Directorate General Information Society of the European Commission, http://www.cordis.lu/ist/fet/qipc-sr.htm). This document has been elaborated, following a former suggestion by FET, by a committee of QIPC scientists to provide input towards the European Commission for the preparation of the Seventh Framework Program. Besides being a document addressed to policy makers and funding agencies (both at the European and national level), the document contains a detailed scientific assessment of the state-of-the-art, main research goals, challenges, strengths, weaknesses, visions and perspectives of all the most relevant QIPC sub-fields, that we report here Y1 - 2005 SN - 1434-6060 ER -