Quantum Integrated Circuits and Electrons Spins in Semiconductor Nanostructures

Proposed schemes of quantum information and computation utilise the spin of the electron either singly or in the form of double/triple quantum dots with more complex spin textures. Single, Double and Triple Quantum Dots can act as qubits in quantum information schemes and the resistance of an adjacent quantum wire is sensitive to electron distribution nearby and so can act as a readout mechanism of the spin configuration such as singlet, triplet and a more general spin state. This will allow Qubits and a Quantum Information scheme to be developed in parallel with the strong electron-electron interaction in the wire which leads to electrons pairing. The operating limits such as temperature, geometry and factors affecting the spin polarization will be investigated and calculated. For example, as the temperature is raised, or the carrier concentration in the wire is lowered, the spin direction becomes increasingly ill-defined and the incoherent regime is reached. The project will involve compound device fabrication and measurements at UCL and collaboration with Hitachi Europe based in Cambridge which has an interest in the project and will provide advice as well as a Placement for the student.