About a possible violation of causality as an alternative to the information interpretation of quantum theory

This is a review of a very interesting (in the authors' view) phenomenon, the operation of the nonlinear light beam splitter. The beam splitter is a flat interface between two transparent dielectrics, at least one of which exhibits Kerr nonlinearity, i.e., its refractive index depends on the transmitted radiation intensity. Interestingly, quantum and classical theories make directly opposite predictions about the phase fluctuation of the output radiation of this device. Even more interesting is the interpretation of the quantum results, which is reduced to the alternative: either the finding of a violation of the principle of causality in the sense of the impact of events subsequent to the previous or appeal to the information interpretation of quantum theory.