Reduced dynamics for entangled initial state of the full density operator
A. J. van Wonderen, K. Lendi · Journal of Physics A Mathematical and General · 2000
Starting from the Schrödinger equation for a system and a reservoir, we construct a quantum dynamical map that describes reduced dynamics. We work with an arbitrary initial state for the system and reservoir, and thus refrain from performing any factorizations. The map is found to be nonlinear, not completely positive, and not unique. To investigate the physical implications, the Bloch equations are constructed. If the freedom the new map offers us is fully exploited, then the classic inequality γ ⊥ ⩾γ ∥ /2 for the damping coefficients must be replaced by a weaker condition.