Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 29 for “"Two level systems"”.
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Scattering of Few Photon Fields by Two Level Systems in a One Dimensional Geometry
… realized strong, efficient coupling of effective two level systems to waveguides. We study the scattering of multimode photons from such emitters coupled losslessly to the confined geometry of a one dimensional waveguide. We develop novel techniques for describing the scattered state of both …
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Low frequency critical current noise and two level system defects in Josephson junctions
… has been known to arise from an ensemble of two level systems connected to the tunnel barrier, the precise microscopic nature of these TLSs remain a mystery. In this thesis we will present measurements of the 1/f low frequency noise in the critical current and tunneling resistance of …
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Experiments to develop High Q and tunable superconducting coplanar resonators applicable for quantum bit technology
… resonant coupling of the resonant frequency with two level systems in the substrate. At T<2.2 K the resonant frequency scales logarithmically with the temperature, indicating that two level systems distributed in the volume of the Silicon Dioxide affect the electric permittivity. Applying higher …
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Quantum Theory of Glasses
… excitations in crystals, supplemented by two level systems which are chemically local entities coming from disorder. This thesis suggests a radical revision of this picture. We argue that the excitations in low temperature glasses are deeply connected to the energy landscape of the glass …
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Phonon thermal transport in metallic glasses below 100 K
… We succeeded in manipulating the density of the two-level systems in our PdSi rods by heat treating them. Since the plateau regime and the ~T2 regime in the phonon thermal conductivity were affected in the same way, we concluded that the plateau and the T2 regimes are both caused by the two-level …
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Dicke enhanced energy transfer via off resonant coupling y Christopher Black.
… hosts a second-order transfer of energy between two collections of two level systems via an off-resonant oscillator. No first-order transfer of energy is possible because the systems are optically isolated. The entire system is placed into a low-frequency simple-harmonic-oscillator (SHO) which …
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The physics of superconducting ring resonators
… experiments and applications over the past two decades. Numerous research on linear distributed, either half-wavelength or quarter-wavelength, and lumped element superconducting resonators, has led to a better understanding of their underlying physics and substantially improved resonator …
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Low Temperature Properties of the Orientationally Disordered Material: Cyanide-Doped Potassium Bromide
… by Anderson, Halperin, Varma, and Phillips for two-level-systems in amorphous materials.
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Low Temperature Properties of the Orientationally Disordered Material: Cyanide-Doped Potassium Bromide
… by Anderson, Halperin, Varma, and Phillips for two-level-systems in amorphous materials.
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The Pressure Dependence of the Low Temperature Thermal Properties of an Amorphous Polymer
… behavior, which is indicative of localized two-level excitations. For temperatures in the range 1 K-10 K there is no widely accepted model to explain the existence of an additional set of vibrational modes or the apparent sharp decrease in phonon mean free path. Some microscopic models for …
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The pressure dependence of the low-temperature thermal properties of an amorphous polymer
… behavior, which is indicative of localized two-level excitations. For temperatures in the range 1 K- 10 K there is no widely accepted model to explain the existence of an additional set of vibrational modes or the apparent sharp decrease in phonon mean free path. Some microscopic models for …
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Universal conductance fluctuations, glassy kinetics, and 1/f noise
… in strongly disordered metallic CCu and SiAu systems was studied in the temperature range 2-300 K. The temperature, frequency, and electric and magnetic field dependencies were found to be consistent with the predictions of the universal conductance fluctuation theory in the low temperature …
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Revisiting physics of quantum bits
… In this thesis, the physics of truncated two level systems is revisited and it is shown that in some systems, such as in triple-junction superconducting flux qubit, environmental noises that are usually recognized to only have dissipative effects and the trivial resultant dephasing, can …
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Electrical noise studies of the re-entrant spinglass nickel-manganese
… a different picture for at least thin film systems with partial short-range atomic order. In this picture it is clusters of spins rather than individual spins that have a random transverse component of magnetization. In addition to these results, electrical noise arising from the dynamics of …
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Microwave studies of amorphous silicon
… The n values observed in this study fall into two ranges: 2.09 -2.36 and 3.26 -3.47. Comparison of measurements at 9.3 GHz and 16.5 GHz indicates that the observed rates are independent or very nearly independent of microwave frequency and applied magnetic field. Conventional one and two phonon …
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Superconducting Microwave Resonators for Low Loss Sensor Applications
… quality factor with readout power when both two-level systems and quasiparticle heating effects cause dissipation. Using scattering parameter theory and adapting the Rothwarf-Taylor expressions, I solve for quasiparticle population and energy stored in a resonator simultaneously. I present a …
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Growth of titanium-nitride thin films for low-loss superconducting quantum circuits
… at high power, consistent with the saturation of two-level-systems (TLS) at high power. These results confirm a connection between the high quality crystalline materials produced in this work and low loss in quantum circuits.
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Quantum Trajectory Theory of Open Cavity-QED Systems with a Time Delayed Coherent Optical Feedback
… of integrated (or solid state) photonic systems, including quantum dots, waveguides, and cavities, has provided a base to harness quantum optic phenomena for use in current and future quantum technologies. These systems also provide opportunities for exploring fundamentally new regimes in …
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Entanglement and control of quantum states
… via resonant inter- action with a sequence of two-level atoms.The preparation is achieved by choosing an appropriate (in general entangled)initial state of the atomic sequence,and does neither require a final state measurement of the atoms,nor a control of the atom-field …
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Resistance fluctuation spectroscopy and other transport behavior in lanthanum barium copper oxide
… the Dutta-Horn model predicts for an ensemble of two-level systems. Additional observations — suppressed power spectral density at high currents and variation of noise with in-plane current direction — suggest that the resistance fluctuations have a stripe-like character. In summary, a process has …
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