  We investigate the effect of different types of non-unitary quantum channels
on multi-qubit quantum systems. For an $n$-qubit system and a particular
channel, in order to draw unbiased conclusions about the system as a whole as
opposed to specific states, we evolve a large number of randomly generated
states under the given channel. We increase the number of qubits and study the
effect of system size on the decoherence processes. The entire scheme is
repeated for various types of environments which include dephasing channel,
depolarising channel, collective dephasing channel and zero temperature bath.
Non-unitary channels representing the environments are modeled via their Karus
operator decomposition or master equation approach. Further, for a given $n$ we
restrict ourselves to the study of particular subclasses of entangled states,
namely the GHZ-type and W-type states. We generate random states within these
classes and study the class behaviors under different quantum channels for
various values of $n$.
