Johri, U.C.Airy, Balwant Singh2020-06-242020-06-242019-08http://krishikosh.egranth.ac.in/handle/1/5810147987I have studied the effect of one and two sided amplitude damping, phase damping and depolarization channels on the Bell’s states. I found that in the case of two sided amplitude damping second state protects more entanglement compared to the first state and in the case of one sided amplitude damping both states protect the same amount of entanglement. In the case of one or two sided phase damping both the Bell’s states protect same amount of entanglement. In the case of two sided depolarization channels both the Bell’s states protect the same amount of entanglement while in the case of one sided depolarization channels, second state protects more amount of entanglement compared to the first. Ihave used weak measurement and quantum measurement reversal to protect entanglement against amplitude damping. I found that by using one or two qubit weak measurement and quantum measurement reversal entanglement can be protected effectively. Either in the case of two qubit weak measurement and quantum measurement reversal or one qubit weak measurementand quantum measurement reversal, second state is more protected as compared to the first state. I also studied the effect of correlated amplitude damping on Bell’s states and found that the memory parameter plays an important role. It helps in the protection of entanglement. I found that in the case of correlated amplitude damping, second state protects more entanglement as compared to the first state. As in the case of amplitude damping, weak measurement and quantum measurement reversal can be effectively used to protect entanglement.I found that in the case of two qubit as well as one qubit weak measurement and quantum measurement reversal, second state protects more amount of entanglement as compared to the first state.ennullThesis