Operational interpretation of the vacuum and process matrices for identical particles

This work overviews the single-particle two-way communication protocol recently introduced by del Santo and Dakić (dSD), analyses it using process matrix formalism. We give a detailed account of importance operational meaning interaction an agent with vacuum – in particular its role description. Our analysis shows that should be treated as operation, on equal footing all other interactions. raises issue counting such operations manner. Motivated this analysis, we apply formalism to capped Fock spaces framework second quantisation, order characterise protocols indefinite number identical particles.