Scalable Spin-Qubit Circuits with Quantum Dots
Final rept. 1 Jun 2001-31 Dec 2006
ILLINOIS UNIV AT URBANA-CHAMAPIGN
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Double and triple coupled quantum dots have been fabricated by planar and vertical technology to contain just a few electrons in each dot. Electron imaging by scanning probe microscopy with the capability of wavefunction mapping in quantum dots has been demonstrated. Gate voltage and magnetic field control of charge and spin states, as well as exchange coupling between electron spins and between electron and nuclear spins have been achieved. Coherent nuclear spin operations and square-root-of-swap operation between two electrons on a time scale inferior at 1 ns have been realized. Meanwhile exchange coupling in various dot configurations has been calculated by realistic simulations in good agreement with experiment. Spin relaxation and decoherence mechanisms in quantum dots have been identified and their time constants measured by spin echo in good agreement with theory. Single-shot read-out of electron spin by charge state correlation has been demonstrated to be very fast and robust to electrostatic noise even at finite temperature exceeding state splitting.
- Quantum Theory and Relativity