Klasik gürültünün kuantum korelasyonlara etkisi

In this thesis, I have studied the problem of the effect of longitudinal and transverse noise on the quantum correlations between two qubits. As the model system, two spin 1/2 particles are considered as the qubits which are placed in a static magnetic field in z-direction as well as a harmonic magnetic field in the x-y plane. Both magnetic field magnitudes are considered to have delta-correlated Gaussian white noise in their magnitude. The behaviour of quantum correlations in a noisy environment has interesting features; in this study I have investigatedtwo most commonly used quantum correlation measures, namely entanglementof formation and quantum discord and found that the considered noise cause an exponential decay of entanglement when the system starts from a maximally entangled state and no entanglement can be created by the considered noise combinations if one starts the system from a product state. The behaviour of quantum discord is found to be more interesting: certain noise combinations can create quantum discord out of zero discord initial states. Furthermore, it is shownthat one can saturate the maximally discordant separable mixed state bound, i.e. 1/3, by subjecting a system with initially zero discord to certain noise combinations.