Masters Thesis Defence by Mikkel Lauritzen – University of Copenhagen

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Masters Thesis Defence by Mikkel Lauritzen

Quantum information theory is a relatively new and rapidly growing field of physics which in the last decades has made predictions of exciting features with no classical counterpart. The fact that the properties of quantum systems differ significantly from classical systems create opportunities for new communication protocols and sharing of information. Within all these applications, entanglement is an essential quantum feature. Having reliable sources of highly entangled qubits is paramount when applying quantum information theory. The performance of these sources is limited both by unwanted interaction with the environment and by the performance of experimental equipment. In this thesis, two protocols which creates highly entangled spin-photon quantum states are presented and imperfections in the protocols are studied. The two spin-photon entanglement protocols are both realised by quantum dots embedded in waveguides. The studied imperfections relate to both the visibility of the system, the ability to separate the ground states, and the branching ratio of spontaneous decay, photon loss and phonon induced pure dephasing. In the study, realistic parameter values are applied which are based on experimental results. It is found, that the two studied protocols are promising and likely to perform well if applied in the laboratory to create highly entangled states.