Theses and Dissertations at Montana State University (MSU)
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Item Rare earth doped crystals for classical and quantum information(Montana State University - Bozeman, College of Letters & Science, 2021) Woodburn, Philip Joseph 'Tino'; Chairperson, Graduate Committee: Rufus L. Cone; This is a manuscript style paper that includes co-authored chapters.High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution photonic signal processing, and quantum-limited sensing. Realization of practical solid-state photonic technologies critically depends on finding materials that offer necessary combinations of optical and spin-state coherence, spectral multiplexing capacity, transition wavelengths, and many other key properties. To realize these advances, we continue to improve the fundamental understanding and control of physical processes that govern ion-ion, ion-spin, and ion-lattice interactions. Furthermore, exploring the role of material chemistry and fabrication in determining the observed properties is crucial. With these motivations, we study a range of rare-earth-doped optical materials using powders and single crystals to understand and optimize the properties relevant to quantum memory, quantum transduction, photonic signal processing, and optical cooling applications. In addition to producing, measuring, and analysing spectroscopic and coherence properties of promising material systems, we highlight the engineering of lattice defects to manipulate both static and dynamic disorder. This work spans nine different REI doped materials: four single crystals, Tm 3+:Y 3Ga 5O 12, Yb 3+:YVO 4, Er 3+:Y 3Al 5O 12, and Er 3+:Y 2SiO 5, and five crystalline powders, Er 3+:LiNbO 3, Tm 3+:Y 3Al 5O 12, Tb 3+:Y 3Al 5O 12, Yb 3+:YAG, and Eu 3+:CaCO 3. These choices are based on material properties unique to each system, need for investigation, or potential for systematic comparison of fabrication methods and stoichiometry. Spectral hole burning (SHB), optical and spin coherence measurement techniques are sensitive quantitative characterization tools, complementing traditional optical, chemical, and structural analysis. We find that coherence and spin lifetimes are especially sensitive to low levels of strain and defects in the crystal, undetected by other methods. Properties of REI doped materials are found to vary by orders of magnitude depending on the source, synthesis, and implementation of the materials. Even mild mechanical processing producing large variations in spin lifetimes and SHB properties. These variations are attributed to low levels of glass-like dynamics in the crystalline lattice introduced by inhomogeneous strain and chemical defects, which can be reduced or eliminated by annealing or improved fabrication. Overall, these studies reveal that SHB or coherence measurements are needed to identify material dynamics and guide the fabrication process to reach the true fundamental capabilities of REI materials.Item Coherent laser studies of nonlinear and transient phenomena in Tb³� activated solids(Montana State University - Bozeman, College of Letters & Science, 1988) Liu, GuokuiItem Thulium ions in a yttrium aluminum garnet host for quantum computing applications : material analysis and single qubit operations(Montana State University - Bozeman, College of Letters & Science, 2008) Zafarullah, Ijaz; Chairperson, Graduate Committee: Wm. Randall BabbittRare-earth-doped crystals have been used for optical signal processing and storage applications. In this dissertation, their potential for quantum computing applications is explored. In one quantum computing scheme, information is stored in nuclear spin states and this information is then processed by using optical pulses through the coupling of these nuclear spin states to a common electronic level. To implement this scheme, nuclear spin states and coupling of these nuclear spin states to a common electronic level is required. Preliminary work in rare-earth materials like Pr3+ and Eu3+ has shown promising results regarding their suitability for quantum computing applications. One particular problem with these materials is that their transition wavelengths are only accessible with dye lasers. These lasers are inherently unstable, and currently few available systems exhibit the stability required for quantum computing applications. An alternative choice was to investigate other rare-earth ions like thulium. Thulium has a transition wavelength that can be accessed with diode lasers, which are commercially available, easy to stabilize, and compact. This dissertation is based on our investigations of Tm3+:YAG for quantum computing applications. Investigations involved a detailed characterization of the material. Nuclear spin states, in Tm3+:YAG, were obtained by applying an external magnetic field to the sample. First, interaction of an external magnetic field with the thulium ions at various sites in the crystal was analyzed. This analysis was used to measure the magnetic anisotropy in the material. These results show that it is possible, with the suitable choice of the magnetic orientation and the site in the crystal, to build a working 3-level quantum system. In the demonstration of single qubit operations in Tm3+:YAG, we first theoretically studied the effect of Gaussian spatial beam on the single qubit operations. Later on, we experimentally prepared a single isolated ensemble of ions in the inhomogeneously broadened absorption profile of the medium. This single isolated ensemble of ions was used as a test-bed to implement the single qubit operations. We also isolated two ensembles of ions in the inhomogeneous absorption profile of the medium. The interaction between these two isolated ensembles of ions was also studied.