  Quantum non-Markovianity modifies the environmental decoherence of a system.
This situation is enriched in complex systems owing to interactions among
subsystems. We consider the problem of distinguishing the multiple sources of
non-Markovianity using a simple power spectrum technique, applied to a qubit
interacting with another qubit via a Jaynes-Cummings type Hamiltonian and
simultaneously subjected to some well known noise channels, such as, the random
telegraph noise and non-Markovian amplitude damping, which exhibit both
Markovian as well as non-Markovian dynamics under different parameter ranges.
