Browsing by Author "Lutz, Thomas"

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    Engineered impurity-doped materials for Quantum Information Processing applications - nano-structures and disordered materials
    (2017) Lutz, Thomas; Tittel, Wolfgang; Barclay, Paul E.; Moazzen-Ahmadi, Nasser; Simon, Christoph; Heyne, Belinda Josiane M.; Loncar, Marko; Pierce, Greg David
    In this thesis we explore various ways to extend population lifetimes and coherence times of solid-state emitters. We focus on rare-earth-ion doped host materials and silicon vacancy centers in diamond, both of which are used for applications in quantum information processing and quantum communications. Enhanced lifetimes and coherence times would improve the performance of these applications. One approach investigates the possibility to suppress lattice vibrations that cause decoherence and population relaxation by engineering the phonon density of states through nano-structuring of the emitter's host material. Towards this end we study different materials and methods to obtain the desired nano-materials. Using various optical spectroscopic methods, we show that population dynamics can indeed be influenced by modifying the structure of the surrounding host material. However, we also find that the employed fabrication and synthesis methods often induce crystal damage that, in turn, degrades spectroscopic properties. As a second approach, we study rare-earth-ions in disordered host materials. Detailed spectroscopic characterizations are presented and we show with the example of an erbium doped fiber that such materials can indeed feature better properties, specifically longer population lifetimes, than the commonly used bulk crystals. We found optimal operation parameters for the erbium doped fiber which made it possible to use this medium for successful proof of principle experiments demonstrating a multimode quantum memory that operates within the convenient telecom band (around 1550 nm wavelength). Besides increasing the fundamental knowledge, the results of the studies presented in this thesis are highly relevant for the fields of quantum communications and quantum information processing since nano-structured materials are beginning to be investigated for on-chip implementations of various applications such as quantum memories and quantum gates. In addition, we found that population dynamics driven by detrimental lattice vibrations can indeed be modified in small powder materials and thus, with improved fabrication techniques, the complete suppression of lattice vibrations should be possible, benefiting a plethora of applications.