An exploration of a special case in the relationship between Fisher information and quantum potential in the causal interpretation of quantum mechanics

Abstract

Fisher information is a cornerstone of both statistical inference and physical theory, leading to debate about whether its latter role is active or passive. Motivated by connections between Fisher information, entropy, and the quantum potential in the de Broglie–Bohm causal interpretation of quantum mechanics, the purpose of this article is to derive the position probability density when there a is a close and ubiquitous bonding of Fisher information and quantum potential. This is done by exploring a case in which a particle moves in a straight line and the integrands in Fisher information and expected quantum potential are proportional. It is found that in this case the probability density given by the Schrodinger wave equation has a Laplace distribution and that quantum potential is a negative constant at all points and times. It is noted that the rate of change of the entropy of the particle is bounded above by a limit that is proportional to the square roots of both Fisher information and the absolute value of quantum potential. Unlike Fisher information, quantum potential is a measure of a real physical potential, and it is proposed that it is quantum potential that puts an upper bound on the rate of change of the particle’s entropy and that, being negative in this case, may also act to contain the particle on its straight-line path. It is suggested that Fisher information does not have an active role in the physics, at least in this case, and only provides information about entropy.