http://arxiv.org/abs/1811.00674
Viewing two sources at sufficient distance and angular separation can assure, by light-travel-time arguments, the acausality of their emitted photons. Using these photons to set different apparatus parameters in a laboratory-based quantum-mechanical experiment could ensure those settings are independent too, allowing a decisive, loophole-free test of Bell’s inequality. Quasars are a natural choice for such objects, as they are visible up to high redshift and pointlike. Yet applying them at the ultimate limit of the technique involves flux measurements in opposite directions on the sky. This presents a challenge to proving randomness against either noise or an underlying signal. By means of a “virtual” experiment and simple signal-to-noise calculations, bias in ground-based optical photometry while performing an Earth-wide test is explored, imposed by fluctuating sky conditions and instrumental errors including photometric zeropoints. Analysis for one useful dataset from the Gemini 8-meter telescopes is presented, using over 14 years of archival images obtained with their Multi-Object Spectrograph (GMOS) instrument pair, serendipitously sampling thousands of quasars up to 180 degrees apart. These do show correlation: an average pairwise broadband optical flux difference intriguingly consistent with the form of Bell’s inequality. That is interesting in itself, if not also a harm to experimental setting independence; some considerations for future observations are discussed.
E. Steinbring
Mon, 5 Nov 18
18/49
Comments: 9 pages, 12 figures, submitted