The decay of excited He from Stochastic Density-Functional Theory: a quantum measurement theory interpretation

TL;DR

This paper extends time-dependent current-density functional theory to include environmental interactions, enabling the study of excited state decay in quantum systems, exemplified by helium atom decay, with insights from quantum measurement theory.

Contribution

The work introduces a novel application of stochastic density-functional theory to model decay processes of excited quantum systems, linking it to quantum measurement theory.

Findings

Decay of excited He atoms modeled successfully

Theoretical framework connects decay with quantum measurement

Potential to study other open quantum systems

Abstract

Recently, time-dependent current-density functional theory has been extended to include the dynamical interaction of quantum systems with external environments [Phys. Rev. Lett. {\bf 98}, 226403 (2007)]. Here we show that such a theory allows us to study a fundamentally important class of phenomena previously inaccessible by standard density-functional methods: the decay of excited systems. As an example we study the decay of an ensemble of excited He atoms, and discuss these results in the context of quantum measurement theory.