  We study the non-Markovian quantum interference phenomenon of a multi-state
atomic system coupled to a bosonic dissipative environment by using the exact
master equations derived in this paper. Two examples involving four-level
systems with or without external control fields are investigated. Our results
show that non-Markovian master equations are capable of exhibiting quantum
interference phenomena in a temporal domain that has not fully explored before.
In particular, we show that the environmental memory is instrumental in the
onset of non-Markovian quantum interference pattern in different time scales.
