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 51 for “"spin system"”.
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Obtaining 1D dynamics in a quasi-1D NMR spin system
… the use of NMR. In particular I focused on the system with chains aligned with the magnetic field axis, and with the so-called "magic angle" of 54.7°. In addition, I created a new method of rotation and long RF pulses for NMR spectroscopy. The method cancels off-chain terms of the dipolar …
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Coherence and state engineering of an optically active central spin system
… study of many-body physics in a dense central spin system. It focuses on the development of both the highly coherent quantum-optical platform - a droplet-etched GaAs Quantum Dot (QD) - as well as the techniques to optically induce and probe the collective dynamics of its resident nuclear spin …
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Behavior of the time-dependent Heisenberg spin system Stein's method and physically interesting processes
… dissertation explores the mean field Heisenberg spin system and its evolution in time. We first study the system in equilibrium, where we explore the tool known as Stein's method, used for determining convergence rates to thermodynamic limits, both in an example proof for a mean field Ising …
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MAS NMR of Nuclei with Spin S=1/2 in Polycrystalline Powders: Experiments and Numerical Simulations
… the examination of one-dimensional magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra. These spectra serve as a source of spin-system parameters which are related to structural and conformational parameters. It is to show that all spin-system parameters can be derived in a …
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Coherent control of dipolar coupled spins in large Hilbert spaces
Controlling the dynamics of a dipolar-coupled spin system is critical to the development of solid-state spin-based quantum information processors. Such control remains challenging, as every spin is coupled to a large number of surrounding spins. In this thesis, we primarily focus on developing …
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Dynamics and NMR implementation of controlled-NOT gates for quantum computing
… at a variety of tip angles (angles between the spin and the axis of magnetization) by applying a selective RF pulse of constant power and variable duration. From this collection of spectra, the effective Hamiltonian of the spin system was derived and found to contain an internal Hamiltonian. In …
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Relaxation of the 1-2 and 2-3 transitions in ruby
The interactions by which a System of paramagnetic ions maintains thermal equilibrium with the crystal lattice containing them have been studied experimentally by both non-resonant and resonant methods.12 A resonant pulse method was employed in this investigation because it allows a direct …
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Exploring large coherent spin systems with solid state NMR
… (NMR) allows us to explore a large coherent spin system and provides an ideal test-bed for studying strongly interacting multiple-spin system in a large Hilbert space. In this thesis, we experimentally investigate the spin dynamics in a rigid lattice of dipolarly coupled nuclear spins using …
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The 1H and 13C dynamic nuclear polarization (DNP) enhancement for novel silica phase immobilized nitroxide (SPIN) samples
… that silica phase immobilized nitroxide (SPIN) radical system are advantageous in the SLIT experiment. In favorable cases (e.g. DCCI₃/SPIN system) a ¹³C DNP enhancement 60 times in excess of the high magnetic field (4.7 T) magnetization has been achieved.¹² However a number of factors …
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The Active Site Structure and the Substrate Specificity of Cytochrome P-450(cam)
… is in the maintenance of substrate dependent spin state regulation. Both of these hydrogen bond probes afford a mixed spin system with a decrease in the maximal high spin species obtained.
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COMBINING QUANTUM TRAJECTORIES AND TIME-DEPENDENT VARIATIONAL MONTE CARLO FOR MANY-BODY OPEN QUANTUM SYSTEMS
Simulating quantum systems is complex due to the “curse of dimensionality”, which is exacerbated in open quantum systems that interact with their environment. Indeed, tra- ditional computational methods struggle with the exponential growth of Hilbert space in these systems. This thesis introduces …
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Electron Spin Echo and Millimeter Wave Epr Studies of Disordered Solids
Electron spin echo (ESE) spectroscopy has been used in the first section of this study to measure weak nitrogen hyperfine coupling in a series of pyridine derivatives loosely bound to bis(benzoylacetonato)copper (Cu(benzac)$\sb2$) in solution. The ESE technique has also been employed to study weak, …
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X-ray and neutron scattering studies of the Rb₂MnF₄ and Cu₁âõxMgx̳GeO₃ in an external magnetic field
… in a magnetic field on an extrapolation of the spin-flop phase boundary into the paramagnetic phase, Heisenberg critical behavior can be accessed to a much longer correlation length than had previously been achieved for a high-spin system. Comparison of our results with current theories indicate …
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Tuning the coherent electron-nuclear interaction in a semiconductor quantum dot
… provides a natural realization of the central spin system, as it interacts with the ∼ 10^5 nuclear spins that compose the quantum dot. Ideally, this system can be used to implement a multi-qubit register formed by collective excitations of the nuclei surrounding the electron, or to probe …
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Superprobability on Graphs
… free field. The Gaussian free field is a spin system (or sigma model) that takes values in Euclidean space; in this work, we generalise the classical isomorphism theorems to spin systems taking values in hyperbolic and spherical geometries. The corresponding random walks are no longer …
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The sensitivity of nuclear magnetic double resonance
… irradiation, evidence was found that the finite spin diffusion rate caused a double resonance energy transfer rate under continuous search field irradiation about 30% less than the transfer rate which would be observed if the spin diffusion were infinitely fast. A theoretical explanation of the …
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Modulation and cross-relaxation effects on the lineshape of strongly saturated nuclear magnetic resonance in solids
… explained the lineshape by assuming that the spin system in the rotating frame can be divided into two parts which have unequal temperatures, and which are able to cross relax. For two limiting cases, large HI' and HI small, but still large enough to saturate, we have calculated the lineshape …
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Statistical physics of error-correcting codes
… codes. We map the decoding problem onto an Ising spin system with many-spins interactions. We then employ the replica method to calculate averages over the quenched disorder represented by the code constructions, the arbitrary messages and the random noise vectors. We find, as the noise level …
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Decoherence In Quantum Dot Charge Qubits: The Role Of Electromagnetic Fluctuations
… coupled quantum dots creates a `pseudo'-spin system with the same qubit behavior as the more natural two level system of a single electron spin. The excess electron in the double dot system is restricted to one of the two dots, thereby creating two separate and distinct states (usually …
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Electronic structure of strongly correlated low-dimensional spin ½ systems: cuprates and vanadates
… The model visualizes the interplay of the spin-orbit coupling and crystal field splitting. In the fourth chapter we calculated the electronic spectrum of the single Zn impurity in CuO2 plane considered as a vacancy in Cu 3d states. The analytic solution for the states of different symmetry …
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