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 44 for “"phase coherence"”.
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Phase coherence in the regime of bilayer exciton condensation
At a total filling factor of one two closely-spaced two-dimensional electron systems (2DES) can be viewed as a Bose-Einstein condensate of excitons, where electrons from one 2DES couple to vacant states from the other 2DES. The pairing of electrons and holes (i.e., excitons) is mediated by Coulomb …
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An X-ray study of charge-density-wave pinning and a measurement of the thermal conductivity in blue bronze
… reported in this thesis, pinning of the CDW phase by lattice imperfections was examined. Pinning determines most of the dynamics of CDW systems and can be characterized by a phase coherence length L. Pinning sites were introduced into blue bronze by electron irradiation, then the anisotropy …
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Quantum-coherent transport in low-dimensional mesoscopic structures and thin films
… quantum interference phenomena and quantum coherence in mesoscopic systems, and quantum transport as well as magnetotransport in various materials system. One overarching aim is exploring the different mechanisms that give rise to quantum phase decoherence in lithographically patterned …
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On the Typical and Average Contributions to the Persistent Current in Mesoscopic Rings
… flux. This effect follows from the extended phase coherence of the conduction electrons in this disordered mesoscopic system. As with transport phenomena, this thermodynamic effect demonstrates sample-specific as well as ensemble-averaging qualities common to mesoscopic physics. With few …
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Coherent manipulations of trapped 88Sr+ using the 4D5/2 --> 5S1/2 transition
… percent, and Ramsey inteferometry indicates that phase coherence decays with a time constant of 342±6/[mu]s. Because the laser's dominant spectral broadening occurs on a slow timescale, phase coherence can be maintained by spin echoes for over 5ms. In addition, laser pulses detuned to the first …
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Quantum transport in mesoscopic systems of Bi and other strongly spin-orbit coupled materials
… using a two stage deposition procedure. The phase and spin coherence of Bi geometries constrained in one, two, and three dimensions are systematically studied by analysis of the weak antilocalization transport signature, a quantum interference phenomenon sensitive to spin-orbit coupling. The …
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Strongly-interacting fermions in an optical lattice
… placed in a shallow optical lattice, long range phase coherence of this resonance superfluid was inferred from the presence of sharp interference peaks after ballistic expansion. With this observation we have obtained the first evidence of superfluidity of fermions in an optical lattice. A loss …
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Multichannel maximum entropy method of spectral analysis applied to offshore structures
… method. Cross-spectral estimates of magnitude, phase, coherence squared, and transfer function are calculated. These estimates are then used in mode shape identification of a triple decked, single caisson offshore platform. The superiority of the multichannel Maximum Entropy Methods relative to …
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DEVELOPMENT OF QUANTUM TECHNOLOGIES FOR QUANTUM COMMUNICATION
… Since TF-QKD encodes information in the optical phase, maintaining phase coherence is crucial. In collaboration with INRiM, an active phase-noise cancellation system for TF-QKD has been implemented and tested, demonstrating stable phase coherence over two 50-km fiber spools. Moreover, field …
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Phase dynamics and magnetic field response of proximity-coupled superconductor arrays
… XYmodel, show interesting behavior relating to phase coherence, fluctuations, and dynamics. Our samples display a broad transition to zero-resistance at a field-dependent temperature Te(H). Present theories explain the transition at Te (in zero field) as an unbinding of pairs of …
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High-temperature superfluidity in an ultracold Fermi gas
… of the surrounding particles. Superfluidity and phase coherence in these systems was directly demonstrated throughout the crossover via the observation of long-lived, ordered vortex lattices in a rotating Fermi mixture. Finally, superfluidity in imbalanced Fermi mixtures was established, and its …
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Multi-terminal Josephson effect
… to electrical gating, magnetic field, and phase bias. All observed effects are described by the scattering formulation of the Josephson effect generalized to the case of N>2. Our observations indicate superconducting phase coherence between all the terminals which establishes the Josephson …
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Inhomogeneous 1H NMR spin-lattice relaxation in the organic superconductor κ-(BEDT-TTF)2-Cu[N(CN)2]Br
… is driven by thermal fluctuations in the phase of the superconducting order parameter. Below Tc, these fluctuations take the form of bound vortex-antivortex pairs that have no long-range effect on the phase. At Tc, they undergo a Kosterlitz-Thouless unbinding transition; the unbound …
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Discerning nonlinear brain dynamics from EEG : an application to autistic spectrum disorder in young children
… direction, mainly computing spectral power and coherence. Perhaps due to methodological limitations, together with high variability within and between the cohorts investigated, results have not been in complete agreement, and it is therefore still the case that the diagnosis of ASD is based on …
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Quantum information applications of frequency upconversion
… photon detection. We also demonstrate the phase coherence of the upconversion process, which enables it to convert photonic qubits from one wavelength to another, potentially allowing quantum networks of disparate operating wavelengths to communicate efficiently. This quantum “transduction” …
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Coherent control of dipolar coupled spins in large Hilbert spaces
… between different pairs and extend the coherence lifetimes within the two-spin system. This is achieved without decoupling the stronger interaction between the two spins within a pair. We thus demonstrated that it is possible to restrict the evolution of a dipolar coupled spin network to …
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Nanoscale engineering of spin-based quantum devices in diamond
… characteristics, including long-lived quantum phase coherence in their electron spin degrees of freedom, available highfidelity control and readout at the single-spin level, and strong interactions with other quantum systems such as photons. In addition, color centers can be controllably …
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Quasi-condensation in low-dimensional Bose gases
… suppressed density fluctuations, but whose phase fluctuates strongly. It is shown that modified mean-field theories based on a symmetry-breaking approach can even characterise phase coherence properties of such a quasi-condensate properly. A correct description of the transition from the …
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RF instrumentation and system design for coherent control of anisotropic hyperfine-coupled electron/nuclear spin qubits
… storage and computation due to their long coherence times, while the electron is used as a spin actuator for initialization, information transfer, control, and readout. This is the first implementation of a local processor using the central qubit architecture. In this work, a robust …
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Manipulating Bose-Einstein condensates with laser light
… of this method allowed the determination of the coherence length of the condensate, which was shown to be equal to its size. Spontaneous, off-resonant Rayleigh scattering was studied by exposing an elongated condensate to a single off-resonant laser beam. Highly directional scattering of light …
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