Before revision:  This problem arises implicitly in many nonequilibrium statistical physics scenarios, e.g., when designing processes to implement some desired computations , feedback-control protocols, and Maxwellian demons. However it is known that many such conditional distributions P over a state space X cannot be implemented using  master equation dynamics over just the states in X.
After revision:  This problem arises implicitly in many nonequilibrium statistical physics scenarios, e.g., when designing processes to implement some desired computations , feedback-control protocol, or Maxwellian demon). It is known that many such conditional distributions P over a state space X cannot be implemented using master equation dynamics over just the states in X.