Abstract

The issues, raised in Żukowski (arXiv:0809.0115v1, 2008), concerning the relevance of the von Neumann theorem for the single-system’s quantumness test proposed in Alicki and Van Ryn (J. Phys. A: Math. Theor. 41:062001, 2008) and performed for the case of single photon polarization in Brida et al. (Opt. Express 16:11750, 2008; arXiv:0811.3376, 2008) and the usefulness of Bell’s inequality for testing the idea of macroscopic quantum systems are discussed in some details. Finally, the proper quantum mechanical description of the experiment with polarized photon beams is presented