Statistical moments for classical and quantum dynamics: formalism and generalized uncertainty relations

TL;DR

This paper develops a formalism based on statistical moments to analyze classical and quantum dynamics, highlighting the sources of quantum effects and deriving inequalities that constrain quantum information.

Contribution

It introduces a moment-based formalism that explicitly distinguishes classical and quantum effects, including new uncertainty relations for high-order moments.

Findings

Identifies two sources of quantum effects: distributional and operator non-commutativity.

Derives a large class of inequalities and uncertainty relations for high-order moments.

Analyzes specific Hamiltonians with unique classical and quantum evolution properties.

Abstract

The classical and quantum evolution of a generic probability distribution is analyzed. To that end, a formalism based on the decomposition of the distribution in terms of its statistical moments is used, which makes explicit the differences between the classical and quantum dynamics. In particular, there are two different sources of quantum effects. Distributional effects, which are also present in the classical evolution of an extended distribution, are due to the fact that all moments can not be vanishing because of the Heisenberg uncertainty principle. In addition, the non-commutativity of the basic quantum operators add some terms to the quantum equations of motion that explicitly depend on the Planck constant and are not present in the classical setting. These are thus purely-quantum effects. Some particular Hamiltonians are analyzed that have very special properties regarding the evolution they generate in the classical and quantum sector. In addition, a large class of inequalities obeyed by high-order statistical moments, and in particular uncertainty relations that bound the information that is possible to obtain from a quantum system, are derived.