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Showing 1 to 15 of 15 for “"Cooper pair"”.
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Visualizing Cooper Pair Formation on the Atomic Scale in High Temperature Superconductors
… hotly debated issue is the temperature at which Cooper pairs first form. Do pairs form at the critical temperature Tc or do they form at higher temperatures lacking phase rigidity? To answer the question, we have developed new techniques, based on scanning tunneling microscopy, to visualize the …
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Counting nonequilibrium quasiparticles in a superconductor
Superconductivity is based on the Cooper pairing of electrons, which enables flow of electrical current without resistance, expulsion of magnetic fields in the Meissner effect, as well as electrical circuits obeying the rules of quantum mechanics. Such superconducting circuits are currently under …
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Investigations of Crossed Andreev Reflection in Hybrid Superconductor-Ferromagnet Structures
Cooper pair splitting is predicted to occur in hybrid devices where a superconductor is coupled to two ferromagnetic wires placed at a distance less than the superconducting coherence length. This thesis searches for signatures of this process, called crossed Andreev reflection (CAR), in three …
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Some properties of the magnetic response of mesoscopic superconducting rings
… and internal degrees of freedom of the Cooper pair which takes place when the size of the system becomes comparable to the characteristic decay length of the pair wave function. We show that this phenomenon provides a universal mechanism for distinguishing between odd and even parity …
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Investigations of nonlocal transport and current noise in mesoscopic normal metal-superconductor hybrid structures
… of entangled spin-singlet electrons provided Cooper pairs can be split without losing wavefunction coherence. In Cooper pair-splitter devices the electrodes (or quantum dots) are coupled to a superconductor with a separation of less than or equal to the superconducting coherence length. At …
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Some Topological Aspects of Condensed Matter Physics
… unit of angular momentum associated with every Cooper pair. The problem is also studied using an effective Action approach. Edge currents in a quantum spin Hall model in graphene are also studied using similar techniques. A model for the integer quantum Hall effect on a square lattice is …
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Determing the Properties of Dense Matter: Superconductivity, Bulk Viscosity, and Light Reflection in Compact Stars
… star cores. We derive an effective theory of Cooper pair quasiparticles from a microscopic theory of nucleons, and calculate the coupling strengths between quasiparticles. We then calculate the structure of magnetic flux tubes, taking into consideration interactions between neutron and proton …
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Interacting Fermi Gases
… instabilities, generalisations of a Cooper pair containing more than two fermions, and then a theory of superconductivity is built from these instabilities. This multi-particle superconductivity is shown to be energetically favourable over conventional superconducting phases in …
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Investigation of half-quantized fluxoid states in Sr2RuO4 mesoscopic superconducting rings
… the total anti-symmetric property of the Cooper pair wave function, Sr2RuO4 is theoretically suggested to have angular momentum and form domain structure with order parameter that corresponds to . For micron-size samples, only a few number of domains would exist and signatures of domain …
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Theory of voltage oscillations in ultra-small capacitance Josephson junctions
… which are the result of the periodic transfer a Cooper pair of charge 2e across the junction. This thesis examines certain theoretical aspects of these Bloch oscillations. Chapters 1 and 2 contain an introduction to the physics of Josephson junctions and Bloch oscillations. Chapter 3 introduces a …
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Charge dynamics in superconducting double dots
… of a two level manifold of even charge parity Cooper pair states, and continuous bands corresponding to charge states with single quasiparticles in one or both islands. These devices are fabricated using shadow mask evaporation, and are measured at sub Kelvin temperatures using a dilution …
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Quantum technologies with superconducting artificial atoms
… efficiency is shown to be around 70% in the Cooper Pair Box. Optimization strategies are also discussed. In chapter 4, a novel technique for population transfer in a Lambda system is proposed, nicknamed chirped STIRAP (cSTIRAP), its key asset being the possibility of operating with an always …
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Quantum Hall Tunnel Junctions: Luttinger Liquid Physics, Quantum Coherence Effect and Fractional Quantum Numbers
Submitted by Meng Tao (mengtao2@illinois.edu) on 2012-10-23T18:51:21Z No. of bitstreams: 1 Kim_EunAh.pdf: 1380167 bytes, checksum: ab1df1bef794c23bd5fbb9cd2183882e (MD5)
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Coherent Nanostructures: Dynamics control and noise
… in a class of superconducting nanode-vices named Cooper Pair Box. This is done in chapter where Design and control requirements to achieve large e fficiency are discussed, and a new figure of merit is introduced to characterize the tradeoff between effi cient coupling of the control and noise. …
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Manipulating superconductivity in cuprates with selective ultrafast excitation
… of the Josephson plasma mode associated with Cooper pair tunneling between sets of planes. Above T_c, the same excitation induces a transient plasma mode at frequencies comparable with the Josephson mode. Five compounds were investigated, four in the underdoped regime and one at optimal …