Coherence properties of bulk matter

TL;DR

This paper proves that bulk matter remains at most semiclassical and coherence-preserving in the thermodynamic limit, using density functional theory and quantum fluid dynamics, with implications for understanding quantum coherence in large systems.

Contribution

It establishes a rigorous connection between quantum fluid dynamics and density functional theory, demonstrating coherence stability in bulk matter through a novel theoretical framework.

Findings

Bulk matter is at most semiclassical in the thermodynamic limit.

Coherence stability is maintained via Landau damping.

Higher order quantum effects can disrupt coherence under certain conditions.

Abstract

We prove a theorem, using the density functional approach and relying on a classical result by Lieb and Simon on Thomas-Fermi model, showing that in the thermodynamic limit bulk matter is at most semiclassical and coherence preserving. The connection between quantum fluid dynamics and density functional theory in the formulation due to Kohn and Sham play a significant role leading to a Vlasov-Poisson system of equations for the Wigner function. Coherence stability is achieved by noting that small oscillations in bulk matter are damped by Landau damping. In some conditions the initial Wigner function could generate an opposite effect and coherence stability can be lost involving higher order quantum effects for a macroscopic body.