Quantum Computingin Spin Nanosystems

• Published in: Handbook of Nanophysics pp. 21 - 42
• Format: Book Chapter
• Language: English
• Published: United Kingdom CRC Press 2011; Taylor & Francis Group
• Subjects: Condensed matter physics (liquids & solids); Materials science; Nanotechnology; Quantum Computer; FET Device; Heavy Hole; Circularly Polarized; Linear Polarization; MTO; Molecular Magnets; Excess Electron; Semiconductor Quantum Dots; Atom Light Interaction; Photonic Crystal; Faraday Rotation; Electron Spin; Spin State; Quantum Computing; Quantum Teleportation; Light Hole Band; Quantum Dot; Quantum Logic Gates; RKKY Interaction; Conduction Band; Jaynes Cummings Model; Grover Algorithm; Decoherence Time; Quantum Computing Scheme
• ISBN: 9781420075502; 1420075500
• DOI: 10.1201/9781420075519-7

Before contemplating the physical realization of a quantum computer, it is necessary to decide how information is going to be stored within the system and how the system will process that information during a desired computation. In classical computers, the information is typically carried in microelectronic circuits that store information using the charge properties of electrons. Information processing is carried out by manipulating electrical œelds within semiconductor materials in such a way as to perform useful computational tasks. Presently it seems that the most promising physical model for quantum computation is based on the electron’s spin. A strong research e˜ort toward the implementation of the electron spin as a new information carrier has been the subject of a new form of electronics based on spin called spintronics. Experiments that have been conducted on quantum spin dynamics in semiconductor materials demonstrate that electron spins have several characteristics that are promising for quantum computing applications. Electron spin states possess the following advantages: very long relaxation time in the absence of external œelds, fairly long decoherence time τd ≈ 1 μs, and the possibility of easy spin manipulation by an external magnetic œeld. ›ese characteristics are very promising1.1 Introduction ... 1-1 1.2 Qubits and Quantum Logic Gates ... 1-2 1.3 Conditions for the Physical Implementation of Quantum Computing ... 1-3 1.4 Zeeman E˜ects ... 1-3Jaynes-Cummings Model 1.6 Loss-DiVincenzo Proposal ... 1-7RKKY Interaction 1.7 Quantum Computing with Molecular Magnets... 1-9 1.8 Semiconductor Quantum Dots ... 1-12Classical Faraday E˜ect • Quantum Faraday E˜ect 1.9 Single-Photon Faraday Rotation ... 1-141.10 Concluding Remarks ... 1-20 Acknowledgments ... 1-20 References ... 1-20since longer decoherence times relax constraints on the switching speeds of quantum gates necessary for reliable error correction. Typically quantum gates are required to switch 104 times faster than the loss of qubit coherence. Spin coherent transport over lengths as large as 100 μm have been reported in semiconductors. ›is makes electron spin a perfect candidate as an information carrier in semiconductors (Adamowski et al., 2005).