Quantum control of finite time disentanglement in Qubit-Qubit and Qubit-Qutrit systems [Elektronische Ressource] / von Mazhar Ali

Quantum Control of Finite-time Disentanglement inQubit-Qubit and Qubit-Qutrit SystemsVom Fachbereich Physikder Technischen Universit¨at Darmstadtzur Erlangung der Wu¨rdeeines Doktors der Naturwissenschaften(Dr. rer. nat.)genehmigteD i s s e r t a t i o nvonMazhar Ali, M. Phil.,aus Mansehra (Pakistan)Darmst¨adter DissertationDarmstadt 2009D17Referent: Prof. Dr. rer. nat. Gernot AlberKorreferent: Prof. Dr. Robert RothTag der Einreichung: 25. Mai 2009Tag der mu¨ndlichen Pru¨fung: 13. Juli 2009iiDedicated to the loving memory of my mother (Ammi):Pari Jaan Jhanghiri.&To my dearest brother and wellwisher (Bhai jaan):Dr. Liaqat Ali.iiiivAbstractThis thesis is a theoretical study of entanglement dynamics and its controlof qubit-qubit and qubit-qutrit systems. In particular, we focus onthe decay of entanglement of quantum states interacting with dissipativeenvironments. Qubit-qubit entanglement may vanish suddenly whileinteracting with statistically independent vacuum reservoirs. Such finite-time disentanglement is called sudden death of entanglement (ESD). Weinvestigate entanglement sudden death of qubit-qubit and qubit-qutritsystems interacting with statistically independent reservoirs at zero- andfinite-temperature. It is shown that for zero-temperature reservoirs, someentangled states exhibit sudden death while others lose their entanglementonly after infinite time.