Comment on "Effect of entanglement on the decay dynamics of a pair of H(2p) atoms due to spontaneous emission"

TL;DR

This paper critiques previous experimental claims about atomic decay times in entangled states, emphasizing the need for a more rigorous approach to accurately measure lifetimes in such quantum systems.

Contribution

It provides a critical analysis of prior lifetime measurements in entangled atoms and proposes a more rigorous method for their evaluation.

Findings

Coincidence time spectra are correctly interpreted.

Lifetime measurements assuming independent photon emissions are questionable.

A revised experimental approach is suggested for accurate lifetime evaluation.

Abstract

Tanabe et al (Phys. Rev. A {\bf 82} 040101(R) 2010) have experimentally demonstrated that the emission properties of unstable atoms in entangled and product states are different. The authors define an apparent decay time as a fitting parameter which falls below the lifetime of the single atom for entangled pairs. We argue that their results about coincidence time spectra are correct, but those concerning lifetimes cannot be considered conclusive because they assume the emission of photons by the two atoms to be independent processes, a doubtful hypothesis for entangled states. We suggest an improved evaluation of the lifetimes based on a rigorous approach, which demands some modifications of the experimental procedure.