In their original framework weak values must be measured by weak measurements that are minimally disturbing, meaning that the coupling between an investigated quantum system and a measurement device has no influence on the evolution of the system. However, under certain circumstances this weakness of the interaction is not necessary. In that case weak values can still be exactly determined from the statistics of the outcomes of arbitrary-strength generalized measurements. Here, we report an experimental procedure for neutron matter-waves that extends the notion of generalized eigenvalues for the neutron’s path system to allow the exact determination of weak values using both strong and weak interactions. Experimental evidence is given that strong interactions outperform weak ones both for precision and accuracy.
T. Denkmayr, J. Dressel, H. Geppert-Kleinrath, Y. Hasegawa, S. Sponar, Weak values from strong interactions in neutron interferometry, Physica B Condens. Matter. 551 (2018) 339–346, doi: 10.1016/j.physb.2018.04.014.
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