If the system starts from a pure state o the evolution of the open system can be pictured as a" tree"of trajectories of pure states WAWWY At each time step tn=nAt, the effect of WoWV∠ the environment can be regarded as the action of the jump operator Wi with probability pi p→区= The master equation evolution is Wy recovered by averaging the trajectories according to their probabilities pi(1)pi(2). Pi(n) WYo19 At each time step tn=nΔt, the effect of the environment can be regarded as the action of the jump operator Wi with probability pi: If the system starts from a pure state Ψo the evolution of the open system can be pictured as a “tree” of trajectories of pure states:    i i W W 1 → pi  Wi Wi  + = The master equation evolution is recovered by averaging the trajectories according to their probabilities: pi(1)pi(2)…pi(n)