The Schrödinger–Newton equation as a possible generator of quantum state reduction

It has been suggested by Diósi and Penrose that the occurrence of quantum state reduction in macroscopic objects is related to a manifestation of gravitational effects in quantum mechanics. Although within Penrose's framework the dynamics of the quantum state reduction is not prescribed, it was suggested that the so-called Schrödinger–Newton equation can be used to at least identify the resulting classical end states. Here we analyse the extent to which the Schrödinger–Newton equation can be used as a model to generate a full, time-dependent description of the quantum state reduction process. We find that when supplied with an imaginary gravitational potential, the Schrödinger–Newton equation offers a rationalization for some of the hitherto unexplained characteristics of quantum state reduction. The description remains incomplete however, because it is unclear how to fully recover Born's rule.