An article by the University of Waterloo talks about Quantum Entanglement Harvesting and possible novel applications, such as using it to probe the structure of spacetime: https://uwaterloo.ca/institute-for-quantum-computing/news/entanglement-harvesting-vacuum So I understand that Spacetime and the Quantum Vacuum are 2 ways of referring to the same thing, and that the Quantum Vacuum is composed of entangled virtual particle-antiparticle pairs. But this is the first time I'm hearing this phrase "entanglement harvesting", and I just want to better understand what it means and what its most useful applications may be. How does this entanglement harvesting work? Are they talking about in the presence of an applied electromagnetic field? Is this something that's long been known about, or is it something new?