A general framework for complete positivity

Understand

Complete positivity of quantum dynamics is often viewed as a litmus test for physicality, yet it is well known that correlated initial states need not give rise to completely positive evolutions.

• This observation spurred numerous investigations over the past two decades attempting to identify necessary and sufficient conditions for complete positivity.
• Here we describe a complete and consistent mathematical framework for the discussion and analysis of complete positivity for correlated initial states of open quantum systems.
• This formalism is built upon a few simple axioms and is sufficiently general to contain all prior methodologies going back to Pechakas, PRL (1994).