Two-level quantum system (Qubit) and non-classical states of light such as single photon and superposition of coherent state are under special attention in quantum technologies such as quantum computing, quantum communication and quantum computers. Hence, behaviour of two-level system driven by such inputs is important. In this study, the behaviour of two-level quantum system driven by vacuum state, single photon and superposition of coherent state was investigated by assuming Pauli matrices as system operators in quantum filtering equations. The purity of conditioned and unconditioned states is also analysed when the system is driven by different inputs. The results show that the stochastic master equation (ME) dynamic has more information about the status of system than ME dynamic
