Subject: [Qirg] General question on photon heralded entanglement

From: JW <[email-masked]>
Date: Mon, 10 Sep 2018 14:58:26 -0400

I was curious about larger entangled structures, for example a molecule of entangled atoms, and stumbled upon several examples of heralding the mutual entanglement of literally thousands of atoms with only a few (or a single) photon(s).
While this seems very impressive, what would be a real-world application?  One article hinted at finer atomic clock resolution but had no significant details.  With the no-cloning theorem in play, beyond 'the most atoms pocketed in a single shot' aspect, what am I missing?  It seems as if everything was well under control (polarity, spin, etc.) prior to any measurements, and the very complicated matter of injecting and measuring individual photon(s) for an outcome was simply a statistical formality.
Can this still be considered quantum entanglement, or is it just a way of quantifying the volume of aligned atoms and their collective deviation?

Thank you in advance,John