Comment on 'Contextuality in Bosonic Bunching'

摘要

Kurzynski et al. proposed a system that allegedly violates the exclusivity principle. As illustrated in Fig. 1 in Ref. Three bosons are pairwisely combined at a beam splitter at which they bunch and leave in the same random output mode. The events qb, bc, and ac [in which k (k) denotes particle k being reflected (transmitted)] are conjectured to be pairwisely exclusive, since the reflection of a excludes its transmission. All event probabilities being 1/2 due to bunching, the sum 3/2 violates the exclusivity bound of unity and saturates the bound allowed by no disturbance. However, following the authors' reasoning, the three events are not exclusive, which disproves the conclusions of Ref. The attribution of exclusivity to the three events relies on assumption (ⅱ): "The scattering properties of each boson on the BS [beam splitter] do not depend on which other fiber is connected to the other BS's input port and on the choice of the BS's input port." (all quotes taken from [1]). Essentially, assumption (ⅱ) states that particles must propagate independently. Such strong assumption is unreasonable to impose on physical theories, since it excludes any interaction. It is violated already by classical systems, and by particles described by quantum mechanics that interact either via a potential or by an effective bosonic (fermionic) exchange interaction.