On the Formation of Lines in Quantum Phase Space

TL;DR

This paper investigates how quantum states in phase space tend to form line patterns in Wigner distributions, revealing their connection to coherence, interference, and grid states, which differ from classical phase space behavior.

Contribution

It introduces the concept of randomized grid states as the cause of line formation in quantum phase space and analyzes their stability and relation to interference phenomena.

Findings

Lines in quantum phase space arise from state coherences.

Randomized grid states explain the formation of straight line patterns.

Higher-order 'eye' patterns are less common and deform into lines upon randomization.

Abstract

We study the formation of lines in phase space in Wigner's distribution $W.$ Whereas lines in phase space do not form in classical systems, unless special initial states are chosen, we find, for large classes of systems and initial states of quantum systems that $W$ tends to form straight line patterns crisscrossing phase space. These arise from the states' coherences. Some of those lines have astonishing extent, reaching across the entire state. We show that the formation of such straight line patterns is due to the formation of 'randomized grid states'. We establish their stability to perturbations, and that they are tied to interference phenomena in configuration space. We additionally identify generic higher-order `eye' patterns in phase space which occur less often since they require the formation of more specific regular grid states; and we show that the randomization of eye patterns tends to deform them into lines.