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Module 2 – Quantum Computing and Quantum Coherence
The topics of the planned research in Quantum Computing and Quantum Coherence are:
- manipulation of single spins
- decoherence of spin-qubits
- study of entanglement in nanostructures
The Manipulation of single spins requires the development of new materials such as patterned
ferromagnetic structures and g-factor modulation. New techniques using scanning probe microscopes with
magnetic tips to manipulate spins will be investigated. Scanning probe microscopes will also be used to
study the charge profile in quantum dots, which can help to better understand the spin states. Another
important topic is the optical control and detection of spin-qubits, which offers promising alternatives
to the electronic transport schemes.
For the decoherence of a single-qubit, the first goal is the complete theoretical understanding of
the decoherence mechanisms in e.g. GaAs quantum dots and in open structures such as 2DEGs and nanowires, and
to identify the dominant sources of decohrerence. Experimentally, the objective is to monitor single-spin
decoherence, using electron spin resonance and resonant microwave excitation. Our knowledge on decoherence
will be used for our second goal, which is to find out ways to reduce spin decoherence. For instance, we
will investigate experimentally the efficiency of nuclear-spin cooling for the suppression of decoherence
induced by hyperfine interaction. The third goal is to move to more complex situations and gain better
theoretical understanding of systems where two or more qubits are coupled with each other, as is required
in quantum computing schemes.
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Quantum dots on parabolic quantum wells |
For the theoretical and experimental study of entanglement in nanostructures we will investigate the most
promising schemes to create and detect entanglement in semiconducting dots and wires, and in
superconductors. One key question is to determine whether the decoherence of entangled qubits is stronger
than the single-qubit decoherence.
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