Effect of noise on quantum coherence and non-Markovianity

In this thesis, we have studied the quantum coherence and non-Markovianity of a two-level system whose energy level is modulated by Gaussian noise, and also its tunneling barrier is fluctuated by a random telegraph noise (RTN). We have investigated the system dynamics by solving the Liouville-von Neumann equation. Using analytical methods, we have obtained the exact solution of the two-level system considered in the thesis for very limited parameter values. We can summarize the important findings of the thesis as follows; (i) for two different initial states, the coherence is found to exhibit damped oscillation behavior, (ii) in the presence of a high Kubo number, we discover non-Markovian dynamics, (iii) It is also found that there is no strong relationship between system coherence and non-Markovianity dynamics, with the exception of a region where these two quantities start to change their characters at K = 1 for two initial states.