  Relying on an exact time evolution scheme, we identify a novel transient
energy transfer phe- nomenon in an exactly-solvable quantum microscopic model
consisting of a three-level system coupled to two non-Markovian
zero-temperature bosonic baths through two separable quantum channels. The
dynamics of this model can be solved exactly using the quantum-state-diffusion
equation formalism, demonstrating finite intervals of unidirectional energy
flow across the system, typically, from the non-Markovian environment towards
the more Markovian bath. Furthermore, when introducing a spatial asymmetry into
the system, an analogue of the rectification effect is realized. In the long
time limit, the dynamics arrives at a stationary state and the effects recede.
Understanding temporal characteristics of directional energy flow will aid in
designing microscopic energy transfer devices.
