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 19 of 19 for “"Spin Chain"”.
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Investigation of Frustrated Quasi-One-Dimensional Quantum Spin-Chain Materials
… configuration) quasi-one-dimensional quantum spin-chain compounds. Both compounds crystallize with tetragonal structures containing edge sharing CuO6 octahedra chains which experience Jahn-Teller distortions. The basal planes of the octahedra link together to form CuO2 ribbon-chains which …
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Quantum Matter in the Era of Generalized Symmetries
… recipe to compute the SymTO data for any lattice spin model, demonstrating it in a number of examples. We then use the SymTO to classify possible quantum phases allowed by the symmetry—we call this a generalized Landau paradigm. Besides classifying phases, we also identify constraints on the phase …
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Prethermalization and localization in quantum spin chains
… ordered (OTO) correlations in nuclear spin systems with magnetic resonance techniques. Hamiltonian engineering enables tuning the strength of spin-spin interactions and of a transverse magnetic field in a spin chain system, as well as to invert the Hamiltonian sign to reveal OTO …
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Obtaining 1D dynamics in a quasi-1D NMR spin system
… 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 Hamiltonian in …
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Grundzustandseigenschaften von anisotropen antiferromagnetischen Heisenberg-Ketten mit Spin S = 1
In this thesis ground state properties of S = 1 spin chains with exchange and single-ion anisotropy are analysed. Following earlier publications two cases are mainly considered: A fixed ratio of the two anisotropies as well as a fixed and strong exchange anisotropy. The method primarily employed is …
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Scaling up a quantum register of dark electronic spins in diamond
Electronic spin defects in the environment of an optically-active spin can be used to increase the size and hence the performance of solid-state quantum registers, especially for applications in quantum metrology and quantum communication. Previous works on multi-qubit electronic-spin registers in …
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Interacting Anyons in One and Two Dimensions: Strong Zero Modes in Anyon Chains and Non-Abelian Anyons on a Torus
… of strong zero modes in non-abelian anyon chains. We show a Tambara-Yamagami chain is equivalent to a Zn chiral clock model. We then present numerical evidence for a strong zero mode in an SU(2)4 anyon chain. By rewriting the chain as an XXZ spin chain, we construct the zero mode explicitly …
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Decoherence effects in nonequilibrium transport through mesoscopic systems
… Of particular interest are systems where the spin degree of freedom of the electron plays an important role because their investigation might lead to the development of a new class of electronic devices in the future. Relaxation and decoherence of the electron spin, which result from the …
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Inelastic light scattering in low-dimensional spin systems
… from a number of low-dimensional quantum spin systems using Raman spectroscopy have been presented. The main motivation of this thesis is to hunt for new types of elementary excitations which may be present in low-dimensional spin systems with exotic spin topology. The studied systems can …
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Delocalization phenomena in strongly disordered systems
… point. Through a mapping to a disordered spin chain, we provide a real-space description of the topology of the ground state and the delocalized state that emerges at the critical point. In this case, the mechanism that leads to delocalization reveals an unconventional type of …
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Local conservation laws in quantum integrable systems
… method is then applied to two quite different spin-chain Hamiltonians, the XXZ and Hubbard models, and shown to successfully generate all of the known local conservation laws of these models and some new ones.
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Dynamics of quantum many-body systems with long-range interactions
… resonantly enhanced long-range tunnelings onto a spin chain with peculiar interaction terms. We study the novel properties of this system in and out of equilibrium. The second main topic is the dynamical growth of entanglement and spread of correlations between system partitions in quench …
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Finite and infinite matrix product states for Gutzwiller projected mean-field wavefunctions and their applications to quantum spin systems
… ground states of 2D or quasi-2D quantum spin systems has been an important research theme in recent years. Many of these states show exotic quantum orders that cannot be understood in the context of Landau-Ginzburg order parameters. With few exceptions, 2D analytical calculations are not …
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Aspects of spin-charge separation in high Tc cuprates
… resistivity in optimally doped cuprates, the "spin gap" phenomena, and antiferromagnetic fluctuations. Some of the basic features of the high Tc, phase diagram can be readily understood from slave boson mean field theories of the t-J model that yield a variety of phases like the uRVB phase …
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Generating and protecting high fidelity multi-particle entangled states with atom-photon interactions
… and next-nearest-neighbor terms in a 1D spin chain. Tuning these couplings allows one to access a host of interesting phases and quantum phase transitions, including the exotic deconfined quantum criticality (DQC) phenomenon. We introduce methods for using targeted laser exciations to …
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One-Dimensional Quantum Magnets in Cuprates: Single Crystal Growth and Magnetic Heat Transport Studies
… κ_mag, of the one-dimensional two-leg spin ladder system Sr_14Cu_24O_41 and the spin chain system SrCuO_2. These two S = 1/2 antiferromagnetic Heisenberg compounds possess enormous magnetic contributions to the heat transport which in some cases exceed the phonon contributions by more …
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Topological phases, non-equilibrium dynamics and parallels of black hole phenomena in condensed matter
… with two broad topics - Majorana modes in Kitaev chain and parallels of black hole phenomena in the quantum Hall effect. Majorana modes in topological superconductors are of fundamental importance as realizations of real solutions to the Dirac equation and for their anyonic exchange statistics. …
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Doping Studies of Frustrated Magnets
… is one of the simplest quasi-one dimensional spin-1/2 magnets which can be modelled with ferromagnetic(FM) nearest neighbour and antiferromagnetic (AFM) next nearest neighbour interactions. Here, doping with both non-magnetic ions, Zn, Mg, and magnetic ions, Co, is investigated. LiCu1-xMxSbO4 …
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Cluster mean-field dynamics of the long-range interacting Ising chain
… the dynamics of the long-range interacting Ising chain using a cluster mean-field approach, a mean-field theory that accounts for short range correlations. The principal result is that, if the system is isolated from an external environment, the model exhibits two different behaviors depending on …