Quantum correlations and nonprojective measurements underlie a plethora of information-theoretic tasks, otherwise impossible in the classical world. Existing schemes to certify such nonclassical resources in a device-independent manner require seed randomness-which is often costly and vulnerable to loopholes-for choosing the local measurements performed on different parts of a multipartite quantum system. In this Letter, we propose and experimentally implement a semi-device-independent certification technique for both quantum correlations and nonprojective measurements without seed randomness.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
June 2015
Two natural requirements on a measurable quantity possessed by a paraxially propagating light-field to be suitable for free space optical communication are invariance under free space propagation and invariance under transverse plane rotation. While the former invariance ensures that the measurable quantity is robust while signalling through free space, the latter invariance ensures that a detector measuring the quantity can be oriented at any angle in the transverse plane, and a measurement by the detector yields the same value for the quantity irrespective of the transverse angle, thus avoiding alignment issues. The variance matrix of a paraxially propagating light-field is analyzed from the perspective of the aforementioned invariances.
View Article and Find Full Text PDF