Passive realism in the presence of open system dynamics
The study investigates if open system dynamics can restore 'no-signalling in time' (NSIT) when testing passive realism, which assumes pre-existing properties are passively observed. The core finding is that NSIT is only restored universally if the initial state is maximally mixed or the channel is a discard-and-prepare channel; otherwise, binary measurements violating NSIT are guaranteed to exist.