Nuclear interference by electronic de-orthogonalisation

TL;DR

This paper demonstrates that in coupled electron-nuclear systems, non-adiabatic correlations can dynamically generate interference in nuclear density, revealing a new signature of quantum correlations in composite systems.

Contribution

It introduces a novel mechanism for nuclear density interference caused by electron-nuclear correlations within the exact factorisation framework.

Findings

Interference arises dynamically in nuclear density from non-adiabatic correlations.

Interference has no counterpart in adiabatic evolution.

Nuclear interference is a signature of correlated quantum motion.

Abstract

Interference is a universal consequence of superposition, yet in composite quantum systems it can encode correlations between subsystems. We show that in coupled electron-nuclear dynamics, interference in the nuclear density can arise dynamically even when it is initially absent. Starting from a superposition of orthogonal Born-Oppenheimer electronic states, we demonstrate within the exact factorisation framework that genuine non-adiabatic electron-nuclear correlations induce de-orthogonalisation of the electronic factors, thereby generating interference terms in the nuclear density. Such interference has no counterpart in adiabatic evolution. Unlike conventional nuclear wave-packet interference or interference that merely reflects electronic coherence in a chosen basis, the effect identified here is a manifestation of the compositeness of the full electron-nuclear state. Nuclear density interference thus emerges as a direct dynamical signature of correlated quantum motion in composite systems.