Manipulating Quantum Coherence in Solid State Systems

ISBN-13: 9781402061349 / Angielski / Twarda / 2007 / 234 str.

M. E. Flatt; I. Trifea; Ionel Trifea

Opis

The lectures at the NATO Advanced Study Institute Manipulating Quantum Coherence in Solid State Systems presented a fundamental introduction to three solid-state approaches to achieving quantum computation: semiconductor spin-based, semiconductor charge-based, and superconducting approaches. The purpose in bringing together lecturers and students in these disparate areas was to provide the opportunity for communication and cross-fertilization between these three areas, all focusing on the central goal of manipulating quantum coherence in solids. These proceedings present detailed introductions to the fundamentals of the ?rst approach and the third approach, and as such bring together a fundamental pedagogical treatment of the two areas which have progressed the furthest towards realizing a scalable system of manipulable qubits. Semiconductor spin-based approaches to quantum computation have made tremendousadvancesinthepast severalyears. Individual spinshavebeen succe- fully con?ned within self-assembled quantum dots and lithographically-formed quantum dots. Within the self-assembled quantum dots the spin lifetimes have been measured and shown to be longer than 1 ms at low temperature. Lithographic dots have been used to controllably reorient nuclear spins in order to lengthen the spin lifetimes. These exceptionally long spin lifetimes should permit many spin operations (qubit operations) within a decoherence time. Coherent spin transfer has also been demonstrated between two colloidal dots connected by polymer chains. Spins can be localized on dopant atoms, such as manganese atoms in gallium arsenide. These spins can be oriented, manipulated and detected with a- electrical means. Electrical techniques can also be used to manipulate nuclear spins, and eventually to drive nuclear magnetic resonance."

Spis treści

Preface. List of Participants. Semiconductor Spintronics for Quantum Computation. 1 Introduction. 2 Spin-dependent processes in electrical transport. 3 Spin Coherence Times in Semiconductors. 4 All-electrical control of single ion spins in a semiconductor. 5 Single-spin manipulation in quantum dots. 6 Spin-selective Devices Conclusion; M.E. Flatté.- Many-body effects in spin-polarized transport. 1 Drift-diffusion theory for charge. 2 Drift-diffusion theory for collinear spins. 3 Spin Coulomb drag - an introduction. 4 Drift-diffusion theory - continued. 5 Simple applications. 6 Microscopic theory of spin Coulomb drag. 7 Experimental observation of spin Coulomb drag. 8 Spinmass. 9 Spin Hall effect. 10 Conclusion; G. Vignale.- Nuclear spin dynamics in semiconductor nanostructures. 1 Introduction. 2 Hyperfine interaction and spin relaxation times. 3 Dynamic nuclear polarization. 4 Induced magnetic fIelds. 5 Overhauser frequency shifts. 6 Summary. A Table of Semiconductor Isotopes. B Parabolic quantum wells; I. Tifrea. Spin Coherence in Semiconductors. 1 Introduction. 2 Electrical Generation and Manipulation of Spin Polarization. 3 The Spin Hall Effect. 4 Spin Accumulation in Forward-Biased MnAs/GaAs Schottky Diodes. 5 Spin Coherence in Quantum Dots; J. Berezovsky et al.- Quantum computing with superconductors I: Architectures. 1 Introduction. 2 The basic qubits: phase, flux, and charge. 3 Fixed linear couplings. 4 Tunable couplings. 5 Dynamic couplings: Resonator coupled qubits; M.R. Geller et al.- Superconducting qubits II: Decoherence. 1 Introduction. 2 Single qubit decoherence. 3 Beyond Bloch-Redfteld. 4 Decoherence in coupled qubits. 5 Summary; F.K. Wilhelm et al.- Index