It probably sounds absurd, but I heard such expressions as "subtracting a particle from vacuum", or from squeezed vacuum, in the context of quantum experiments, or quantum optics, (not black holes). Can someone give me an example of situation in which a particle is subtract from vacuum? Further, if such a phenomenon is possible, are there processes made possible due to energy taken from the vacuum?
Again, classically it seems absurd, but is there any quantum process I which the answer is "yes"? (I looked at other questions that seem related, but I didn't see a sufficient analogy with mine.)
I would appreciate answers as phenomenological as possible, not formulas and formulas.