FAIR SAMPLING VS NO-SIGNALLING PRINCIPLE IN EPR EXPERIMENTS

Guillaume Adenier

K. Hess, Walter Philipp

GUILLAUME ADENIER, NOBORU WATANABE, Andrei Yu. Khrennikov

We propose a local scheme to enhance the security of quantum key distribution in Ekert protocol (E91). Our proposal is a fair sampling test meant to detect an eavesdropping attempt that would use a biased sample to mimic an apparent violation of Bell inequalities. The test is local and non disruptive: it can be unilaterally performed at any time by either Alice or Bob during the production of the key, and together with the Bell inequality test.

Giuseppe Faraci, D. Gutkowski, S. Notarrigo +1 more

Guillaume Adenier, Andrei Yu. Khrennikov

We analyse optical EPR experimental data performed by Weihs et al in Innsbruck 1997–1998. We show that for some linear combinations of the raw coincidence rates, the experimental results display some anomalous behaviour that a more general source state (like non-maximally entangled state) cannot straightforwardly account for. We attempt to explain these anomalies by taking account of the relative efficiencies of the four channels. For this purpose, we use the fair sampling assumption, and assume explicitly that the detection efficiencies for the pairs of entangled photons can be written as a product of the two corresponding detection efficiencies for the single photons. We show that this explicit use of fair sampling cannot be maintained to be a reasonable assumption as it leads to an apparent violation of the no-signalling principle.

Guillaume Adenier, Andrei Yu. Khrennikov

We have previously shown that the use of the fair sampling assumption in EPR experiments could be questioned on the basis of experimental data. We continue our analysis of the data from the optical EPR experimental performed by Weihs et al. in Innsbruck 1997-1998, and we discuss whether a non-rotationally invariant source can account for the experimental results.